I argue that 5e already does handle the concept
Simple numbers illustrate beyond a shadow of a doubt, that the concept is represented to even a tiny fraction of the extent it was in it's original (and still, only) version. It might be handled to your satisfaction - but, as someone who wants the concept excluded entirely, 'to your satisfaction' could mean any handling no matter how poor or trivial, all the way down to 'none at all.'
Besides, the point was that you were claiming it couldn't handle the concept as 4e did because 4e was a different game. Not being able to handle a concept as well as another game is not exactly claiming even parity.
But you were wrong in that assertion: 4e was a different edition of the same game, and it was a much more structured one with more constrained design space. 5e is much more capable of incorporating and handling concepts from other editions, including, trivially, 4e.
Stop denying it that virtue.
Further, the agenda you own up to is merely that you want the Warlord class to be optional. You can rest assured it will be. You could have done so before participating in this thread, as there's no plausible scenario for a class becoming non-optional.
You know, it is interesting how people have a general aversion to this being done via a social stat, but have 0 problem with this being done via a physical stat.
A: "My character is an unstoppable juggernaut!!"
B: "I make a grapple check" <A fails save>
DM: You can't move and must make a check to escape
A: "My character will never give up or surrender!!"
DM: *rolls damage and reduces A to 0 HPs* You are unconscious.
I would really like to know where this disconnect comes from.
Probably from the early days of the game. There weren't a lot of social resolution systems back then, and the ones there were - morale, loyalty, reaction - applied exclusively to NPCs.
If the game is going to treat physical and mental/social traits EQUALLY when a character chooses to invest in them, why should they not have equal game effect?
Because frankly, it seems to me like it is cheating to ignore the results of a bluff roll because of some piece of OOC knowledge when you would never ignore an attack roll because it is equally undesirable to you OOC.
You make a good point. Resolution system in 5e are as functional if one of the 3 mental stats is involved as they are if one of the 3 physical stats is involved.
And the result of that is actually to expand player agency, since you can choose to play a character who is less like you in terms of those 3 stats. You could always play a barbarian much stronger than you, but playing a character smarter, wiser or more charismatic than yourself used to have little bearing on anything beyond spellcasting and henchmen. It's been slowly expanding. In 5e, checks can potentially model such characters quite nicely, assuming the DM rules appropriately when those stats might come up.