Why is one character praised for being overpowered and boring but the other character is hated for having these traits?

it is genre subversion no need to train
no real stakes

>having the strong guy fight at full power all the time is not interesting
Saitama is pulling his punches, that's part of the joke. His 'ultimate move' is called Serious Punch for a reason, he's explicitly not punching as hard as he can.

>tell me when he needs to train
I don't think this is as important to the shounen label as people think. Jojo Part 3-6 have zero training as far as I can remember, and even One Piece mostly shoved all that training into one-panel sidestories set during a timeskip.

Well yeah, but that's not my point. I mean more in the sense that One Punch Man does not find its titular character all that interesting and would rather focus on the characters that are trying their hardest against villains that can hold back against them. Of course he could obliterate Fuhrer Ugly, but he's not here, so we have to ask if any of the weaker heroes can do that.

one punch man is no battle shonen
no matter if you attempt to conflate it

one punch man is shonen and it is comedy
but it is not a battle shonen like dragonball
or my hero academia

Saitama is part of a larger disection of heroism that is central to the themes of the webcomic. Is saitama more of a hero than genos, who actually risks death every fight? Is mumen rider more of a hero because unlike saitama and genos hes dedicated to helping people even though hes relatively powerless? Is king a hero for ultimately facing his fear when he had no intention of even being able to help regardless? Is tatsumaki a hero just because shes powerful and gets paid to help people? Is sweet mask more of a hero for overcoming his evil nature? Saitama is interesting because of how his character affects those around him and how he changes the world hes in on a personal level (or how he fails as the case may be)

100% of the time ive seen superman used hes either been a blatant mouthpiece for the author to shill a moral or hes been evil because "superman do bad thing thing bad". Burger politics are boring and character drama isnt.

Lets just this out of the way first
Webcomic: good
Manga: bad

>he nitpicks while gargling on east cock

It doesn't mean anything. the author only creates fake drama for saitama to solve. Superman challenges are completely different.