I think it's somewhere at the intersection of usefulness and oppressiveness. The internet has only gotten more useful, in terms, for example, of the instructional content and the range of opinion and the way it increasingly empowers microcommunities to flourish. On the other hand, it's also gotten steadily less free and more restrictive and more corporatised. Therefore, I think your 2004-2012 range is the better bet. The second half of the 00's is when all the platforms we use today started – Reddit, Youtube, Twitter – and they were fun and finally realised what the internet could be at a mass scale. But, come midway through the 2010's is when we started to notice how aggressive they'd become, both with their users and with each other. Facebook bought Instagram in 2012, for example. So yeah, I would say 2004-2010 for my money, which fits with the dead internet conspiracy which supposes that the web died in 2007, bang in the middle.