I just liked the vibe and name of Kbin. It reminded me of Kerbin, the home planet in Kerbal Space Program.
I later learned it might be the Polish word for magazine. The "subreddits" here are called magazines, but it could also mean like gun magazine. The latter of which I don't really care for (especially as a US user), but in the end, I don't really gaf. It's just a chill place to hang out.