Sure, to people like you, it has to be “FUD”, rather than experience of using or trying the damn thing.
For over 15 years, I have tried the many Linux distros that have been release, and each time, I come away disappointed. No doubt that, anyone can learn to use any OS, but, ease of use is not what Linux has going for it.
Linux is quite capable, but, it’s not as user friendly as any Windows OS, and, even the latest distros still have people needing to, at times, go to the command line, or having to compile certain code to arrive at a usable program. Granted that, for most of what the regular folks need, they many never have to visit the command line or reach for a compiler, but, it should never have to happen.
Your kids and family may be happy with your Ubuntu, but, when anything goes wrong with the OS or any related hardware or software, you are there to handle the problems for them. Not everybody is going to want to depend on a father or uncle to handle the issues for them with a computer.