It would be a bad idea since if someone acts toxic or posts innapropriate content they could change it into something else so we cannot prove the mods they violated something.
And if they edit it again, it should have in brackets x2, x3, (etc)
Owners of the stream and the site mods would be aloud to see the edit changes, Mods and regular users cannot.
No Blaze is right.
It would be because someone toxic or rude could just change their comment to be nice and innocent while the defender or other person arguing with them would seem like the aggressor, making them get the comment ban instead. So having a little "Edited" next to the hours would be a nice way to know