I upvoted here because I think the question is certainly a valid one to ask, but not because I agree with the solution.
Allowing a single user to ask an unlimited number of questions in a given period of time opens an easy door for spam--with the current question limits, a spambot with an account here can post a maximum of $50$ spam posts in a $30$ day ...
You may be interested in the feature request Preventing misuse of question self-deletion
Posting a question and then deleting it invisibly counts against the user; if they do it enough, they will be question-banned.
If you really want to ignore someone, try Ignore Users Script. I haven't tested it myself.
The point to the time-limit for edits is not to prevent somebody from changing what they commented after five minutes as an end in itself.
Rather, the point of the time limit is to guarantee some integrity of a conversation in comments without having revision-histories for comments.
As long as there is no conversation this is a non-issue. Of course, ...
I think a very short period is reasonable.
This is because unlike "posts", we do not keep a publicly accessible (in fact, not even a moderator-accessible) history of comment edits.
5 minutes is already a pretty long time on the internet.
With a longer period I see at least three problems:
Do not cross the streams! The conversation in the comments can ...