What you are seeing is the internet in its true form. Trekkies and computer nerds are the only native fauna of the internet, everyone else is an invasive species.
It does work tho. In the past six months, I've became a proud Linux champion and really enjoy it. It's a nice change from Reddit celebrating women getting punched in the face.
Also by disabling anime, porn, news, star trek, star wars, lord of the rings and for some fucking reasons bluey and you can go through top day in an hour or somethin lol
I'm not denying the preponderance of those two subjects, but there's plenty of other things too, even if you filter/block most nsfw stuff like I do. Mind you, there are days and times where new posts get scarce, but I think that's a good thing that indicates lemmy users aren't as addicted as other forums can be.
If you like trains then there are a few slightly active communities you can help contribute to. Just an example of a niche on Lemmy I'm trying to grow.
Filtering all the nerd shit from Lemmy is like ordering a big mac with no mac. Or a whopper with no whop. Or animal style fries with no animals. It just doesn't work.