I'd just add that I don't expect it to reflect 'normal D&D'. I expect it to reasonably reflect many D&D games. I welcome others using different reasonable assumptions that reflect many other D&D games as well. I'm personally as interested in learning more about the criteria martials and casters balance out in damage as I am about exploring the merits of the argument that Fighters are strong enough in combat that they don't need anything else.
Honestly, I don't think it's very relevant. Whether fighters are superior in the general sense in combat to casters isn't really a big deal. I'm not sure who brought it up, either.
But I do think martials do have, in my experience, better capabilities in combat in a general sense, even at higher levels. It's really about damage, HP, and AC.
While casters can compete if they're exceptionally equipped and attentive, there's a lot of room for error.
For example, a common idea for a caster is to turn into a high HP, high con character like a dragon via true polymorph. Well, a classic example would be the Ancient White Dragon. Good HP, Good AC, and Good damage...but not really.
See compare it to a Barbarian at level 20. The barbarian will have 285 HP, but since their rage halves the majority if damage, even magical, they'd effectively have 570 HP. Their AC would be around 24. And the damage they dish out, especially if they're a Frenzy Barb, would be about 52 damage. The dragon does admittedly better damage at a whopping 109 damage, though it's mostly physical damage which may be immune or resistant.
It's important to know that a polymorphed dragon cannot use magic items at all. So, if you're fighting a tarrasque, the dragon doesn't do anything until their breath weapon recharges.
edit:sorry, my phone was acting weird.