I kind of wish that there was a bot that could auto-validate that at post time for communities that want it.

Doesn’t even have to be a hard ban on any changes (like, I think that cleaning up garbled ISO entities in titles or stripping trailing website names from titles is entirely reasonable), but just compare title and submitted title, and if they differ, add a top-level comment with the original title.

On Reddit, I remember that /r/Europe eventually took a pretty strict line on that after people kept editorializing titles.