You're imho too pessimistic. I think we don't need to take away freedom to solve the particular problem of rude/non-constructive behaviour. Feedback to every single talk edit can probably solve the thing without having to force people not to participate in every discussion. For example, multiple choice (definitely yes/yes/a little/not at all):
Do you think this contribution:
- Is relevant for the discussed subject?
- Is relevant for the project's goals?
- Is friendly/nice?
If a small mark shows next to all your talk edits, you will think twice before commenting. I think the whole problem of rude behaviour can be erased without having to forbid participation.