Here are some replies from Jonah in a related previous discussion - Fedora is not a user friendly Linux Distro - #21 by jonah
I’m personally against adding Ubuntu, considering the criteria currently and the list of recommended distros (there are a lot and i think they ‘cover’ a lot of desired use cases), for me it comes down to the release model. And recommending something like Debian testing channel doesn’t help with the usability complaint
*edited to fix link and elaborate:
I actually don’t mind Ubuntu too much myself (i use it when i need a temporary, maximum ‘just works’ distro), I just think including it in the recs alongside the distros with the edge in privacy and security by default would cloud the reasons why some are recommended over others.
IMO it could be worth including a section about Ubuntu more specifically on the Knowledge Base page about Linux, since it is by far the most popular distro and discussing the issues with it from PG’s perspective could help people make a more informed decision about using it.
Currently there’s actually no mention of Ubuntu directly at all.