Probably the main point is that these are the last guys to qualify, the elite, top ten in most weights, have already qualified. Amature boxing is very, very strong right now. The top boxers have ten or more fights a year against other top boxers, not cherry picked, many at semi-pro level. Only a special pro could win an Olympic gold now.
I tried to bring up this point about GGG and Hagler one day and somebody called me an idiot. I think it was Drenlou.