The lemmy feed has gotten better, and I think it's intended to mimic Reddit's feed somewhat, but it still seems to include a ton of posts from popular communities that seem to drown out the less popular ones.

So if you're looking for new communities, all will probably not be a very efficient way to do it since you'll need to sift through a ton of content from more popular communities (and your new niche community won't be popular at the start).

Also, and I could be wrong on this, I think it only shows posts from communities your instance tracks. So if nobody on your instance has looked for a given community, it won't appear in all unless it happens to be hosted on your instance. I haven't verified that, just that's how I expect it to work given how other things on Lemmy work.

So the better solution seems to be to use a directory like this one and search for communities that way. That's what I do, and it seems pretty effective. I browse through that periodically and find interesting communities that way.

And yeah, it's cool that lemmy let's you do it, I just personally don't find a ton of value there, at least not as this point. Maybe it'll be more useful once communities have stabilized a bit more and the feed itself has matured. But for now, it just seems like a ton of noise to me.