Well, we don't actually know when big mom blew up. As far as words go, I usually do these late at night, so I am tired as balls. Tsuru does look like a grandma at this point, or did you forget she aged worse than Garp and Sengoku? Vegapunk should have begun his work on devil fruit factors at this point, so it's not impossible, but I'll give it to you, maybe giving queen his laser was a bit of a stretch. But at the same time, it's never stated that queen uses kizarus lasers. It's always been referred to as just a laser. The main character is raised by one of the strongest characters in the series, and we see what only two years of that looks like with Kobys' growth. So, the main characters being ridiculously strong makes perfect sense, as Shanks is ridiculously strong. I also include high bounty pirates simply because there aren't many other big named pirates. Plus, the seas are constantly being made fun of for being weaker than what they used to be. That means the quality of pirates has decreased since rogers era. Everything else you said, is fair criticism though.

MC & Brago never had a life & death battle, it was proven that battles strengthen OP Characters more than just years of training. Rob Lucci went to assasination missions even as a kid. Kidd pirates grew up in a dangerous place. Shanks grew stronger due to his fights in the New World, he used to be on par with Buggy back in Roger's crew, but Buggy stayed in East Blue so he stagnated. Although I'm all up for power ups, it just didn't go gradually. And felt so unearned imo. Fighting a calamaties or a Sweet commander level opponent as a recruit, is just ridiculous.

Yeah and 2 years with Garp made Koby go from wimpy and weaker than kids to a captain in the marines, where he's out here fighting the blackbeard pirates. that simple feat alone shuts down your entire argument.

on contrary, it completely proved my argument. Yes it made him at Smoker level, but that's simply the limit of the Blues. Smoker spent a decade with negligible improvement in Logue town. Yet when he went to Grandline, he ushered to a vice admiral level just from having those dangerous fights. Same with Koby, it wasn't Garp's training that made him stronger, but stronger enemies and near death experiences.

actually it was a combination of Bogards training, garps training, and his own determination. However, he only had that for two years. Not Six years straight.

sure, Bogard & Garp, people who also needs to fight the sweet commanders and calamities seriously but could easily beat MC & OC with their fist of love. You might as well say Nami is the strongest since she could beat Luffy. If you still can't see why you failed with their "first" battles, then I guess you can't awaken people who pretends to be asleep.