With XFCE though, I'm quite happy with the level of focus stealing, things that seem to be justifiable are at the right level, like authentication prompts.
Out of interest, what are the things that take focus for you? Maybe we're running totally different sets of programs which might give me an impression that isn't warranted.
I've not noticed focus stealing outside of Steam. What is steam made from, it seems very browserish.
This topic is causing some self-reflection and wonder if I am the peculiar one who does different things and just not bumping into it, I mainly work from xterm, screen, mutt, vim and a lot of time in firefox. Perhaps this combination just doesn't start things that request focus, but when in MS Windows I noticed it a lot.
You're right about steam, but now I'm on a path of wondering...
This topic confirms that focus stealing is a thing in XFCE, I have some research to do!
I am baffled as to how that has been allowed to go on so long. It makes Office a trainwreck usability wise.