> This is true for most distros though

Not with secure boot (which I forgot to mention but I have to enable). AFAIK today there is OpenSuse, Ubuntu and RHEL. Last time I checked (about a year ago) there was OpenSuse and that was it.

> I always think the reason is more because they like using a niche distro.

Not at all. First, OpenSuse is not really niche. I don’t care about being edgy (or I would run something like Arch or Gentoo). It just is solid and works well. Again, it’s the robustness-updates balance.