Yes, you're wrong.
I would push back here and say the issue isn't purely one of balance, it's also an issue of gameplay. It's easy to assume it's a balance issue because casters have been stronger than martials for most of D&D's run, but it's not hard to see how balance can be achieved without changing the system of spells as "granted authority" and martial tricks as "ask the DM". Look how much more balanced 5e is than 3.5 to see how that can be accomplished. (Not that 5e is perfectly balanced, but it's much better than 3.5!)
DM fiat can also affect all character equally. DM fiat is dependant on people-to-people interaction, and not from the interplay of the rules themselves.
The inverse is also true! If you want to play a Caster you absolutely need to deal with spell slots, maybe spell prep, and Concentration, and action types... I played a Cleric and a Bard and a Druid and I'm honestly tired of full casters mechanics. Next time I want to be magical I'll play a Warlock and Pew Pew my way to victory with Eldritch beat.
You should try bladesinger.
One hundred percent agree. There should be simple casters (like a Warlock with no spell slots but some extra invocations) and complex warriors (look at the Level Up combat maneuvers for examples) to go along with what we have now.
And not all players who want to play a mechanically straightforward character want to play weak characters. That link needs to die in fire. Playing a simple martial character should not mean playing a mechanically weak character. Though it is interesting that the game has basically always rewarded system mastery with greater direct power in game. Maybe that should stop, too.
So turn the game into a boring slugfest of endless combat? No thanks.
