It can be. Once you get to hyper specific niches, you’ll start seeing communities where it’s more or less only a single person posting, if anyone’s around at all. In more general communities it depends what’s going on. There’s a few people in the memes and shit posting communities who I swear make just about every post that ends up high up on top/day, and are in half the comment sections too. In communities like ask Lemmy it’s usually different people posting, but the same few people replying