Everything you say is right, but it is not the whole story.
Gangnam Style is an example of the use of new media (YouTube) by old players (YT Entertainment / Universal Republic) generating good old fashioned hype via old & new media:
Andy Yeti-Barr has analysed the strategies behind this success story:
"Looking at YG's seeding platform, pre Gangnam, it had circa 2.5m subscribers to its various YouTube channels and had achieved in the region of 1.6 billion views of musicians’ videos across those channels. WOW! Its main artists also, as is expected, have Twitter accounts; the majority that I looked at were mainly channels to push information but with high follower numbers.
These seeding platforms were vital to its efforts. YG knew that its YouTube subscriber numbers alone would mean that it would get high volumes of views from day one. This would take the pressure off them to try and push the story onto media, as media would be dragged in to the story by the high viewing figures.
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To help with this, it contained a kid who had caught the media's attention with his crazy talent during Korea's Got Talent, a famous South Korean comedian (the guy in the yellow suit) and another famous entertainer (the guy thrusting his crotch in the lift scene). These three people, alongside Psy, made for a hugely strong cast and one that would appeal back home
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The video was launched on July 15 2012. It was preceded by two tweets from @allKpop, the twitter account associated with American based AllkPop.com, a celebrity and music gossip site focussed on the Korean music industry
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The video debuted at number one in the Korean music charts, nice!
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The next big push came via Gawker, which wrote a story on the song and video that generated 19k of Facebook Likes/Shares for the article (July 30).
This was followed by Billboard (the site that I suspect triggered the celebrity
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The spike in traffic and views of the video caused YouTube Trends to write a post on Gangnam Style, making it their Video of the Month in terms of views and likes (Aug 7).
Whilst many news pieces started emerging at this time, both in terms of online and broadcast media, SkyNews in the UK was probably the next big, (in terms of influence), channel to run a feature (Aug 13).
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Late on September the 3rd, a YouTube video showed Psy drinking a shot with Scooter Braun, THE Scooter Braun offa Justin Bieber manager fame, seemingly celebrating them working together started doing the rounds.
This was a huge announcement and the media, once again, went into overdrive, with seemingly every gossip and music site writing up the story."
The Gangnam Viral Marketing Style Playbook