Yes, same for lemmy.world. If you want to post something niche and find a dead Lemmy.world community maybe consider first seeing if there's one elsewhere to revive or even make yourself (assuming you're registered somewhere else of course).
Yeah, I have no problem with Lemmy.world (I mean, my main is on here), but spreading comms amongst at least a few instances is better for the overall health of the Fediverse.