Earlier quoted context omitted.
I don't know about you, but I've never had a git repo that didn't have a .gitignore file. Having one automatically would make me do one less step. This doesn't dumb down programming. It improves UX for everybody, while also improving security for beginners. Why does GitHub offer to autogenerate a readme file? Because it's convenient. That doesn't dumb down programming for anybody.
Correct, but having a line that ignores .ssh is bloat in 99.99% of cases. The key word in your second point is 'offer'. If they were to protect these keys from being pushed they would have to interfere with your first push and add a line to your .gitignore, which you would then have to remove EVERY TIME... if your a developer I don't know how at this point your not like "eh, actually I don't really feel like doing th…
However, I agree with your point that allowing new devs to keep making this mistake and just shielding them from it is a bad idea. With that in mind, it might be nicer if GitHub checked for .ssh files on commit and showed a warning within the web app, letting you know what you did wrong.