Part of this is also a misunderstanding of the narrative of casters.Which is where the "the fighter must be supernatural" comes from. You could have the fighter raise his strength and constitution to 30 and you're still going to have people complain it doesn't compare to a wizard's versatility. So if people are serious about "fixing" the problem, give them mythical abilities but explicitly say they are mythical. Then you can hurl boulders, jump mountains and make goblins pee their pants by gaze. But the problem is people still want fighters to do these things but represent Boromir or other nonmythical heroes. They don't want super soldiers or demigods or anything explicitly supernatural BUT they still want fighters to compete with the Masters of the Supernatural in spellcasters. They somehow want Drax and Hawkeye with the same power and versatility as Dr Strange. I'm sorry, I'll buy that Thor is an equal because he's a god or Captain Marvel because she's part Kree, but not "...and I have a bow and arrow" Hawkeye.
People will look at a 20th level wizard and go "yeah that's Gandalf".....but as has been noted in other threads that Gandalf is really more like a 5th level wizard. 20th level wizards are an entirely different narrative animal, moving about the planes as they please, alter reality to suit their whims, etc. That's something WAY WAY WAY more powerful than Gandalf, probably more a Dr Strange.
So we have players going "I want my 20th level fighter to play like Boromir" but we don't have players going "I want my 20th level wizard to play like Gandalf"..