You say 'most great fighters don't lose at 25 years old to gatekeeper C level opposition'... meaning, by definition, some do. And you're correct, some indeed do. Such as Loma, for example...
Loma is a special fighter. He might very well be the boxing GOAT in the making. We've never seen anyone like him in the history of boxing.
P4P is a tricky situation and doesn't carry too much weight. Lamply rated Loma number one and he based it on his assumption that Loma is the hardest fighter to beat in the pros. Other people take a fighters resume as the main source of their decision. Then again, other people ask themselves this question, Who's skills would I rather have no matter what weight I'm fighting at. One can make a case for all three criteria but when they get to the top five it boils down to who they like period because there are pros and cons for each fighter. Only once in a while, a truly great fighter will make himself known and there will be no doubt in anyone's mind who the P4P king is. Mayweather was one of those fighters. Roy Jones was one of those fighters.
Gonzalez isn't better than Lomachenko. Sure I would have liked Walters to put forth an effort against him, but in beating Walters, Lomachenko has beaten two guys better than anyone that Gonzalez has beaten. Gonzalez isn't a pound for pound top three. He was also getting touched up in that title defense before he moved up and fought Cuadras. He's a pound for pound guy, but probably not in the top five in my opinion. Gonzalez will be exposed soon. He's lucky that Frank Warren moved Tete up to bantamweight. I fully expect Inoue, or Cuadras to handle Gonzalez soon. He needs to stop being a diva.
All time ratings take in numerous factors including resume, longevity, greatness ect. Current p4p # 1 rates the guy who is currently the best boxer in the world. There is nothing tricky about it. It has nothing to do with losses resume ect although those things tend to go hand in hand it simply names the guy who is boxing better than every one else. There is no one who is boxing better than Loma right now. He doesn't need to avenge the Salido loss to be #1 which was a dubious loss anyway. Under the circumstances with the weight, fouls, ref and judges it was the most impressive 2nd pro fight performance in history. Those who hold that loss against him are trying to halt the progress of potentially the GOAT. No doubt current p4p # 1 Lomachencko. If any one can come up with some one who is going better I will debate you all day.
P4P essentially means whatever you want it to be. Everyone's got their own recipe. If someone goes purely by the eye test, the case is there for him.
There is no excuse for a 25 year old elite fighter to lose to Salido. Barrera, Pacquiao, Hopkins, Marquez, Duran, etc. Those guys would never lose to a guy like Salido in their prime.
He only lost because 2 judges got it wrong. At the worst it was 6 rds a piece with Loma taking the last rd by 2. If you don't give last rd 10-8 you don't know how to judge a fight. With a decent ref there would have been pts taken for the fouls. He fought a though pro who was 3 divisions heavier. No great fighter in history has debuted with a 10 rd fight then fought 7 consecutive 12 rd world title fights winning different weight titles in 2 of them or even come close. I reckon you guys that hold this loss against him are the same ones that rate FM's win over Marquez.
Just like there was no excuse for a 22 year old future ATG to get KOd by a guy like Singtrupat or whatever the hell his name was.
Agree the general sentiment, but I think it's a bit harsh calling Junior Jones subpar (who I assume you are referring to with Barrera?) Chin apart, JJ was a very good fighter in his day.