Every single large server in this federation has at least one Star Trek community. There is even an entire server dedicated to Star Trek.
Not only that, these communities are some of the most active I've ever seen. There is no other franchise I know of that dominates the federation as much as Star Trek does.
So, what's the correlation with Lemmy and Star Trek? Why not other sci-fi series? Please, are there any connections?? Is this all coincidental?
Same reason Linux is popular on Lemmy. Lemmy is essentially an explicitly leftist community that appeals to people nerdy and techy enough to leave Reddit and join a smaller platform. Linux is a FOSS, ie leftist techy OS. Star Trek is leftist Sci-Fi.
Nerds, tech, and leftism all congregate on Lemmy.