On July 6th, 1972, David Bowie performed 'Starman' on Top Of The Pops. It was a moment which, two years after The Beatles split up, turned the next generation of children and teenagers on to pop music, and it's obvious why. No one watching that broadcast had seen anything like it before, and it filled millions of young minds with questions: Is David Bowie a man or a woman? Is he gay or is he straight? Why is he dressed like that? Is he from Earth or from Mars? Who the hell is Ziggy Stardust? And who the hell is David Bowie?

Imagine if this happened now, if such a peculiar figure appeared in front of 15 million television viewers as they all sat round to have their tea on a Thursday night. By Friday lunchtime there'd be a blog dedicated to unmasking David Bowie. By Saturday morning, forgotten classmates of his would be appearing on chat shows to share their vague recollections of whether or not he was any good at PE. By Sunday, every newspaper in the country would be running special features, promising to tell us who the real David Bowie is. We would be inundated with old school reports, childhood photos, interviews with family friends – anything, in other words, to deconstruct the mystery.

If there was any mystery to be deconstructed in the first place, that is – because wouldn't a modern day David Bowie be chatting shit on Twitter with the rest of his mates in bands? Wouldn't he have a blog where he bores us with details of how his new album's going, complete with Instagram images of different amplifier configurations? Wouldn't his press person have already uploaded his entire life story onto Wikipedia, long before he was appearing on prime time TV?

While once it was what made pop exciting, true mystery is increasingly rare in modern music. It is difficult to achieve and harder to maintain.

There are countless reasons for this, but the internet is an important one. Unlike in 1972, we can hear pretty much any music ever made by simply clicking our way through Google. This means musicians have to compete with centuries' worth of sounds for our attention – so how do they keep people interested, beyond the usual marketing channels? Simple: a few Tweets a day, some funny photos of them on tour and the odd broadsheet newspaper Q+A, so we don't forget they exist and instead feel like we are being given an exclusive insight into their lives.

It's a vicious cycle, because the more of their lives musicians share with fans, the more their fans expect, until eventually the songwriter is about as mysterious as Silvio Berlusconi's sex life, but far less interesting. And of course, eager to feed content-craving music fans is a media industry under insurmountable pressure: innumerable newspapers, magazines and websites desperate to beat the rest by filling their pages with everything from pictures of Ed Sheeran and One Direction playing headers and volleys) to Jonny Greenwood talking about chickens).

In fairness to Radiohead, that article aside, they're one of a dwindling number of musicians who maintain a shred of enigma. Their Twitter feed is cryptic, and you'll struggle to find any paparazzi shots of Ed O'Brien buying a pint of milk in his dressing gown. Oh, and there's their recent habit of making albums without telling anyone and putting them straight online once they're done.

They aren't the only ones using the web, not strictly as a means of interaction with their fans, but as a means of cultivating a mystery. WU LYF, for example, started their career by putting recordings online without explanation, uploading images that made them out to be some sort of street cult, turning down interviews and deleting their Wikipedia page. Conveniently, this approach translated into widespread media coverage and silly levels of hype from every corner of the music press (I believe the technical term is "having your cake and eating it"), but at least it was more interesting than reading another bland redrafted press release on someone's blog. It was exciting.

Similarly, widespread speculation followed a series of music videos that began appearing online under the name iamamiwhoami. The videos were sent to journalists from an anonymous e-mail address and featured an unnamed blonde woman whose face was obscured. Suggestions as to who was responsible for the videos varied from Trent Reznor to Christina Aguilera, until eventually, someone worked out it was a Swedish singer called Jonna Lee and her producer Claes Björklund. The project deservedly won a shedload of awards, though the mystery surrounding it has all but evaporated as Lee began touring the iamamiwhoami album, kin, earlier this year.

There are other examples too, such as mask-wearing electronic producer SBTRKT – who, like WU LYF and iamamiwhoami, declined to be interviewed for this article, the mysterious swines – and once -anonymous dubstep pioneer Burial who, in a bizarre series of articles in 2008, The Sun's gossip goon Gordon Smart made it his mission to unmask. These two give different reasons for their fascinatingly enigmatic ways: Aaron 'SBTRKT' Jerome says he wants to "let the music speak for itself" while William 'Burial' Bevan simply describes himself as a "low-key person".

Indeed, despite all the benefits that a public profile, social media and fan interaction can offer a musician, there'll always be some who decide it's not for them, withdraw from public life altogether and let the myths run wild. For example, until his death in 2006, Syd Barett was the definitive reclusive musician. His music aside, what made him interesting was that he was completely unlike the motormouth rent-a-quote musicians of today. Instead of slagging off new bands in the NME and appearing on the cover of Hello! in a pink suit, he let his legacy remain untarnished and went from cult hero to rock legend (how's your legacy looking, Liam Gallagher?)

More recently, you can look at Jeff Mangum, whose band Neutral Milk Hotel has only become more popular since they split in 1999, and he remained for years out of the public eye. Only recently did Mangum return to live performance, but he certainly hasn't done any interviews, and even as he wandered past the hot dog stands at the ATP Festival he curated in March he looked as iconic and unapproachable as ever. Part of his attractiveness as an artist is undoubtedly the mystery surrounding his personal life, and I have to admit I was a little disappointed when I interviewed his former bandmate Jeremy Barnes, asked him what Jeff had been up to and was told:

"A lot of people think he was kind of like a Syd Barrett character but that's not true at all. He doesn't do drugs, he's a vegan, he takes a lot of vitamins and he draws pictures and records music. It's not a bad way to live."

That's not to say the decline of mystery in music through greater access to musicians can't be a positive thing. There's something amazing about the idea that you can send a message to a singer you love on Twitter (and they might actually write back!) and it can be an incredible feeling to invest in a band you love on PledgeMusic and know that you, in some sense, are a part of the music they are making. But the idea of musicians being less mysterious by being more accessible can also be tokenistic – you can read as many of Lady Gaga's personal blog posts as you like, you're never going to meet her. She's a multimillionaire pop star, so while she can harp on all she likes about her relationship with her fans, they can relate to her life about as much as Britain's teenagers could relate to an alien rock and roll star called Ziggy in 1972.

Which brings us back to Bowie, who was pictured in the Daily Mail a couple of weeks back, shopping in Manhattan. Dressed in a grey hoodie and sunglasses, it wasn't the Thin White Duke as we remember him, but it was a mysterious image all the same. "Has he retired from music?", the article asked, "or is he too ill to work? Why does he so rarely leave his flat? What is he doing in there?" It seems 40 years on from that Top Of The Pops appearance we're all still asking, "Who the hell is David Bowie?"

The answer? I haven't got a clue, and that is something truly special.