Extension or not, .sh or .bash: definitely subjective.

That was the intention of my comment. Because the rest of the post (or most of it for sure) is not subjective.

It's the effect of the extension on USER behavior that's the problem, the OS doesn't care.

Yes, I get it. But in my case I simply give u+x permissions to the script and then run "./script.sh" and then the script will be executed with the interpreter defined in the shebang.