Why is there a five-minute time limit editing comments? I found typos I wanted to correct in a comment I had posted, but it was too late, and I was forced to delete and repost.
The real problem is that, second class citizens that they are, comments do not have a history.
SE lets you edit pretty much everything else at any time because there's edit accountability: At any given moment, we know who changed what, when, and why. This isn't the case with comments — this is why comments can no longer be edited after the standard grace period.
TL;DR; it would open room for much abuse, which is much harder than posts to moderate.
As a solution, you can entirely delete and paste your comment in another one, if it doesn't make any other comments look stupid and mysterious.