Last time I experimented with Linux desktop (maybe two years ago?) I had one silly annoyance with KDE on Fedora. I was running this on a laptop with a regular track pad. I was surprised to find out that tap to click was not enabled by default, I had to click the physical button to mimic a mouse click. Not a big deal I thought - I logged in, went to settings, and found a configuration to enable the behavior I wanted - great. However, this behavior was only enabled for my user. Every time I wanted to log in, the login screen would use the default behavior in KDE, since my user preferences weren't applied until I actually logged in, of course.
I know, of course, that it's an extremely minor thing, but it felt quite representative. It also reminded me that Linux is stuck in this bygone age where it's expected for a computer to be a multi-user system, so of course they can't have a "privileged" user account other than root (and god forbid you'd think of using root as your normal every day user).