Fark is still around too.

A lot of it has to do with the type of folks who were in the initial Lemmy wave; generally a crowd that is more familiar with linux distros than the tuck rule. Not necessarily a bad thing, just a comment on the interests of the type of folks who were more apt to leave Reddit for another platform. Mainstream sports attract a mainstream audience, whom (on the whole) are more likely to stick to a mainstream website. Lemmy will grow but it took years before some of those communities grew to the size they are on Reddit, and it happened then without a comparable mainstream competitor.