I see both points, but then if they cannot make the weight why do that. I think the same day would prevent guys like Chavez fighting too big.
Exactly. If the boxers didn't have an extra day to hydrate, they wouldn't dry out so much. The doctor that was instrumental in getting the same day weigh-in changed later admitted that he made a mistake.
Sorry, I don't have a link but this topic has been discussed on here before. The doctor worked for the NSAC. It may take a little work but google should eventually lead you to the article. I believe it was a discussion on the pros and cons of the same day weigh-in.
I don't understand what you mean by "real weights". I think the fighters using same day weigh-in were fighting closer to their natural weights. In the "old days" of same day weigh-ins, you did not see fighters putting on 15-20 pounds after the weigh-in and before the fight.