I’ve seen people suggest Ubuntu without mentioning Kubuntu, but it seems like most people (especially gamers?) prefer KDE Plasma. I’ve seen people complain about Ubuntu’s GUI and lack of customization, but then no one suggests them to try Kubuntu instead. It seems like people just don’t know that Kubuntu exists.
Also as an aside, people often criticize how slow updates are on Ubuntu/Kubuntu/etc, but if you enable the backports ppa then it’s actually pretty quick!
sudo add-apt-repository ppa:kubuntu-ppa/backports
The distro itself is fine for beginners. But the main advantage of Ubuntu over e.g. Linux Mint or Brazzite or any of the other beginner distros is that if e.g. third-party software has a guide on how to use it on Linux it’s almost always about Ubuntu. That is the real advantage of Ubuntu. Kubuntu doesn’t have that.