I’m not saying Lemmy/Kbin are perfect but fragmentation is a red herring. Reddit has a HUGE degree of fragmentation, look at how many news subs there are or wrestling versus squaredcircle ect. It’s not really an issue either, take the wildly different approaches Games takes to Gaming; each community serves a related, but unique purpose.
The true battle here is userbase and thankfully those numbers are climbing at a sustainable rate. If we ever get into the hundreds of millions of users it won’t matter how many cooking subs there are, there would be enough unique and viable ones that everyone would have just the one they were looking for.