Yep. My main gripe is that due to various developers not catching up with new standards, a users files can be scattered all over the place.
I appreciate that - in theory - %appdata% should contain just a users files, but a number of apps also use it to store program data leading to a huge folder size. My own is >100GB, with some of the largest offenders being python and node dependencies that are not specific to myself, and could really be cached somewhere else.
That doesn't work well for... well, most software I can think of.
Games: I do not want to backup the entire folder to ensure I have my save files. Modern games are huge. I want my saves to be located somewhere easy to get to (for the average user) and be quick to backup, without having to go in and cherry-pick specific files.
There was a good trend of using Documents/My Games, but sadly that seems to have fractured and now there's also Saved Games, savegames, and some software has moved to using %appdata% or just storing saves in the game install location. There's no consistency, it's a real pain in the hole.
DCC software (Blender, Photoshop, whatever): user preferences and config files. Again, I idon't want to backup the entire software, as I'm likely to reinstall it from an official source when migraing/reinstalling to ensure I have the latest updates. However I do want to be able to backup my preferences or plugins easily.
Any software that allows users to customise it: let me backup those preferences without cloning the entire app.
I do wish there was a standardised folder struture for user data, but it's 2023 and the chances of getting Windows/Max/Nix to agree upon and comform to a generic structure as sadly. The only thing I can think of that's the same across platforms is the .ssh folder.
Meanwhile the original game is stuck with rockpox for 8 more months.
I do not enjoy the rockpox.