I add .DS_Store to every repo despite also having it ignored globally. Efficiency beats pristine. I don't want to have to ever think about or deal with it at all.
Emphasis mine. This is the exact mindset I'm referring to, and when applied generally to files in the repo, will bite at some point. Even if you're lucky and it's unimportant/internal enough not to bite users, it will bite contributors. Luckily none of us would be discourteous enough to do this while contributing to another's repo.
If it's my repo then I decide which files are tracked and I don't want any .DS_Store files, nor do I think any person in history has ever intended to track a .DS_Store file.
In a perfect world everyone would add .DS_Store to their global ignore list but since this is not default it necessitates defensive measures.
If you don't add it to .gitignore then I can guarantee at some point a .DS_Store file will be committed to the repo, because the behavior is broken by default.
It would also be nice if Finder stopped generating .DS_Store files and moved that information to metadata on the directory! They had a great opportunity to fix this when they introduced APFS but alas the blight continues.
Emphasis mine. This is the exact mindset I'm referring to, and when applied generally to files in the repo, will bite at some point. Even if you're lucky and it's unimportant/internal enough not to bite users, it will bite contributors. Luckily none of us would be discourteous enough to do this while contributing to another's repo.