Reddit really did benefit from the fall of Digg though - this was about just shy of 20 years ago? Digg was where Reddit is now, thoroughly upsetting its user base with wholesale changes to the content of the site that nobody liked, and Reddit capitalized on that, and stole Digg's thunder.

I think Lemmy can potentially do the same. For a second, it looked like Squabbles/Squabblr was going to be the winner, but the last I checked, they imploded after some controversy.

(I came here from Reddit, incidentally - the user interface is very intuitive.)