I disagree, the internet is full of websites who were on the top of the world until they weren't. Its easy for content creators to post their content on multiple sites. The main moat is the critical mass of users.

/. Used to be the goto tech forum, but now we are all at hn. Digg was the place to be, now its reddit. Audiences can shift surprisingly suddenly.

I confirm. I used to be subscribing RSS on slashdot but it's been rubbish only appearing there since a few years ago.