Counterargument: if we all had an infinite number of opportunities to redo our moments of inadequacy until they were good enough, any person observing another person’s action would still only observe the action once. In effect, any individual would only observe others acting perfectly, but they themselves would experience themselves perpetually acting imperfectly. (In this way it would lead to a world where everyone but you acted without fault, but you yourself, by comparison, observed all of your own blunders.)
Imagine Annie and Bob as an illustration. Annie goes out drinking on Pride Day with Bob and then regrets it, so she goes back in time to redo the night and opts instead to stay home. Meanwhile, since Bob has remained on the same time continuum, Bob only experiences a Pride Day where Annie is absent. In other words, he has no experience of the other person’s backtracking.
One reason traveling back in time could backfire is that there is no limit on how far you could go back. You could travel back in time to before your existence if you thought your life was a complete waste of time. (And this is unfortunately something many people think.) Alternatively, any parent could effectively kill his or her offspring without any consequences by going back in time to the moment they decided to have the kid…and choosing differently. Unless there were some way to regulate time travel to prevent spontaneous disappearances of innocent people, time travel would not only be a bad idea but possibly an immoral one.