Couldn’t github replace all public commits author info email by a [email protected] email automagically ?
You have to configure your own Git client manually. But you can configure GitHub to block pushes from any email other than the no reply email GH generates for you.
You can’t change anything about a commit without breaking the chain of SHA hashes in the commits, which causes pulls to break.
GitHub hides the emails on their web UI, but nothing stops people from pulling the repository with a Git client and looking at the emails in the commit log after doing so.