Ruby on Rails

I don't see any benefit to not including it.

I can understand the argument for placing it in a global .gitignore, but then again, if including it in a project .gitignore prevents future PR rejections because a .DS_Store is accidentally included (and the follow up discussion on "use global gitignore"), then I would call it a win. I feel PR's should be centered around talking about the code itself, and often times get caught up in minor details or overly opinionated discussions about nothing of import. I am in the camp of avoiding that whenever possible.

I can also see arguments for not using a global .gitignore - if you have many projects on your system, this could become difficult to maintain.

Then again, .DS_Store will likely never be included in any repository, ever, but it seems a little nit-picky to me to be over-zealous about not including it in a project .gitignore. I don't think it's going to hurt anyone. People learn about tools on their own time, and knowing, or not knowing, about a global .gitignore is probably *not* reflective of the code quality from that contributor as a whole.

Just my .02.