The difference is that I don’t use standard XDG directories because I loathe dot-files, loathe hidden directories, and so I declare my own environment variables to put everything where I want.
Then Firefox (and ansible, and many others) comes barreling in dropping an unconfigurable dot-directory in my fucking home folder ignoring the perfectly good XDG variables I have set.
It is a constant struggle to stop my home folder from not feeling like my home. Developers ought to learn some fucking respect.