Yes, in Windows 50% of my day is fighting with something obscuring my view or taking focus. Something pops up just as I was clicking or pressing Enter. I have to sign into multiple systems in the morning and sometimes it takes four attempts to enter creds for one login because I keep getting interrupted. It's infuriating.

you would think they could figured out that programs not directly opened by the user shouldn't be able to steal focus from the program the user is currently interacting with. seems like basic UX/UI failure

You're talking about people who haven't figured out you should be able to edit the options on the right click menu from a single settings menu and that the task bar should expand and contract dynamically with the number of open windows. Microsoft stopped improving the Windows UI around 2006.

desktop user interfaces on all 3 main operating systems peaked by 2010, at that point everything became aimed at clueless cellphone users.

You’re talking about people who use Macs.

This is actually pretty hard to get right. Just yesterday I was confused why opening my text editor under KDE didn't pop up a window. Turns out some update to KDE's focus stealing prevention (or some other involved component) changed things so the new text editor window got pushed behind existing windows.

This isn't an argument for not trying though.

Stealing focus should be a misdemeanor!

This is honestly the worst part of it to me. It happens quite a lot!