Right. And people will argue against it then, like I'm arguing against you now.
Of course. But they will have to agree against WOTCs design choices at that point.
There was a time when they were not separate classes. Then fighter would be used to represent them. Now it really cannot any more. Every time you add a new class, you narrow the conceptual space of the existing classes. By making a separate warlord class, you're saying that conceptually fighter cannot be that any more. I don't want that. I actually like fighters, and I don't want them to carved into separate classes until there's nothing left.
Not really.
You couldn't play a ranger as it is in 5e in the 0e fighter.
You could say it represented them but not
well. And that's the point.
On many representations of fantasy warriors, the fighter as published does a below average job. The question is if it is low enough to the point to mark it as a strike against playing D&D 5e.
The biggest benefit 5e has is that no giant corporation has entered the TTRPG market. So 5e has many strikes it can survive.
But it's not different narrative space. Narratively warlord is a fighter who rises to be a leader and focuses on that. And this supposed 'complex fighter' is even less a separate concept than that. It is simply people being dissatisfied with the rules wanting a new set of rules for a thing that already has rules.
No. A warlord is a warrior that uses their mental ability scores to for combat inspiration, tictics, and insight.
The fighter as built in 5e is too focused on its physical ability scores to advance in combat prowess that it can barely influence combat with his mind.
As for the complex fighter, imma say something controversial.
The "Simple Fighter" should been the Barbarian. The Champion shoulda been a Barbarian subclass. Basic physical brutes should be Martial Barbarians. Barbarians should've been chooses between Rage or Power Strike (I Attack HARDER!!)
The Fighter would be complex by default to represent the Elite Training fighters do.
D&D and D&D is one of the few games that still attempts to combine specially trained warrior and commonly trained ones that happened to be born strong.