Let's see. Either we spend 8 seconds adding it to the project .gitignore, once in the lifetime of the project; or we spend 15 minutes instructing everyone on the team, plus once for every new hire, so they can spend another 30 seconds on modifying their local configuration.

I'm pretty sure I'll never create so many new projects in my entire career that those 8 seconds would add up to the amount of time required to follow your suggestion. Be a little more pragmatic, folks!