Sometimes being a parent is like this too.

But I think the "don't break user space" rule would be more effective if it was very clearly stated and you could point to a doc that made it obvious to the committer that it was against policy.

Linus seems to have a strong internal sense of what the policy means, and he heaps on Monty Python style verbal abuse to get his point across. But while that's good at indicating how angry it is, it's not clear to me that it's the most effective way of reducing violations of the rule.