While I get Stan Lee's point, Marvel still has some semblance of power scaling. For example Spider-Man is the company's most popular hero but he's still consistency shown to get his ass beat by Dr Doom to the point that nowadays he gets scared shitless and doesn't even try.

It shows at least a bit more restraint than how DC has Batman defeating all of the Justice League single handedly due to prep. But in that case you know it's just because Batman is the company's most popular hero by far. Similar to how Joker is one of DC's most feared villains even though he's just an edgy clown.