They are good distros for beginners. But over time some people switch to Arch-based systems or NixOS. Because of HUGE software list that you can install without much hassle, you don't have to add 3-rd party repositories or PPAs or figure out how to install .tar.gz package in your system or how to compile from source. You just type one command to install something hard to obtain in other distros.
I like appimages because they're just a single file/dir and I know where it is on my filesystem at a glance
Could also probably add an appimage to bin pretty trivially