>Not all nostalgia is misplaced. The internet is unquestionably changing, and the trend seems to be that as a system becomes more popular, it becomes more hostile to viewpoints too far from its median

That's not a current trend, that's just statistics. The larger the sample is, the closer it's median is to the median of the whole set of data. It was always this way.

However, people can still build their own smaller on-line communities. With sites like Reddit, it's easier than even. You have r/TumblrInAction, r/ShitRedditSays, and everything in between.