Anecdotal, but I have had bad experiences using Ubuntu. I know it’s not a bad distro, and that it contributes a lot (especially historically), but it’s the other distros that take their contributions and add to it that I find worth using or recommending, or sometimes an unrelated distro. It’s the sort of thing I might give money to, but I’ll never want to use directly.

I think this is what people mean when they say it’s bad - that distros that take what Ubuntu made and add their own touch seem more user friendly.