It depends on what communities and the instances those communities are on. That includes the intentions of the communities themselves. Some are just bots relaying information(certain news communities, tech communities, etc).
So that’s important, and then on top of that it’s important to remember the fediverse is growing, while it’s been around for a number of years it’s still very much new to bunch of people. The amount of users or members compared to twitter, or Reddit(which I’m a refugee from), or facebook, etc is tiny.
So the fediverse is growing and while I love it right now, more and more folks will sign up on different instances and if everything works out the engagement will increase.