There is (at least) two different groups of people using Raspberry PI. One of them are completely new Linux users who need a ton of help and resources to understand enough so they can achieve what they're trying to do. Raspbian/Raspberry Pi OS, even with their faults, is probably the better option for those people, as the environment and context very much takes first time users into account.
NetBSD and Tiny Core Linux, even with all their benefits, is a harder experience to get into if you haven't already dipped your toes into Linux, and doesn't have the same wide community and boundless online resources.