One of the positive aspects about the Mastodon and the fediverse is that, yes, there isn't going to be some mass displacement of Twitter or whatever... but it introduces the ability for all those small niche focused communities to federate and become something larger than the sum of their parts.

Yes, your gamedev Mastodon isn't going to become a mainstream big thing. But it's connected into a broader pool. And that pool has the potential to change the narrative somewhat.