It also keeps them from polluting git status
If anything, I would say that such tricks make git status lie to you. What if you look at the git status and conclude that there are no unchanged files worth tracking and then with that false sense of safety decide to run 'git clean -fdx'? Sounds like an easy way to lose work.
Why is presence of untracked files in git status bothersome to anyone, especially when that is exactly what they are intentionally doing?
(but agreed if you use `-fdx` that doesn't work)