VisualEditor makes it much easier to edit, and part of that is that it makes it easier to add formatting. However, just because something is technically possible doesn't mean it's commonly accepted by local communities and guidelines.
Learning common policies and other Manual-of-Style guidelines is part of the learning curve of any new editor, but there may be some common cases that could raise a flag and warn the user when they do something that's against the guidelines.
- Adding bold text to articles;
- Adding space(s) at the beginning of a paragraph;
- Applying annotations (e.g. links) to trailing punctuation like commas.
I imagine that such a system could easily become a monstrosity of epic AbuseFilter-like complexity, which isn't desirable. But a basic version covering only the simplest use cases might be helpful to guide new editors. Perhaps it could even be restricted to new users.
This isn't something that's urgent, but if it's technically feasible I think it would be welcomed by many editors. If not, then we can get a definitive response either way :)