You misunderstood what I meant by fantasy completely. As in the, fantasy you are playing. As in, the trope. The trope of a fighter and a warlord--I don't see a major difference.
You do have a point with the ideas being similar from a "General Fantasy / Design" point of view. But I simply wanted to emphasize that D&D implements of things weird, for the sake of "Tradition". Even of they are similar concepts, well, "because Tradition" is a thing.
I agree with mellowred: the devs have already decided the 5e "Fighter" must fill the "dumb ordinary warrior" role. So let the fighter have his schtick of second wind and action surge. The Warlord already has enough substance to stand apart.
Look at the existing support classes, by virtue of full access to large spell lists, they can, indeed, do just about anything by default - it's just a matter of picking what they want to do that day. We're not even talking anything the party might need in terms of support contributions, either, since most spells lists include a variety of other functions, as well. That's versatility far in excess of what they had in 4e.
I think the "Warlord should exist" debate should be separated from the "Mundanes are Weak" debate. We should just try to build a Warlord by templating off of other martial classes. It would be the fastest way to integrate a broadly acceptable Warlord into an existing 5e D&D culture. It would fit perfecrly along the lines of "Martials vs Casters" power scale, so that most DMs won't kneejerk insta-ban a Warlord on sight.
You're comparing Martials vs Casters. We need to win the Warlord vs Nothing battle first! Pick your battles wisely.
My viewpoint is that we need to implement Warlords as a "5e Martial class" and not as a "5e Magical Fighter". Right now, a lot of people are playing LowMagic campaigns, and those games don't use the intelligence stat nor have a healer. That's why I keep focusing on an Intelligent & Healing Warlord, because there is a niche that exists.
Conversely, I'm struggling to visualize a "Tactical Warlord" in the 5e framework, so maybe that's where we differ. The 4e warlord did too many "off-turn attacks" and "Situational +1 bonuses" and "Dynamic Dancing Shifting Movements" to be modelled well in the 5e framework. My view is that "Tactical" means like Bardic SongOfRest, or other ShortRest rituals, where the Warlord can grant one-hit bonuses to the next battle to simulate "Tactical Planning & Prep". That's why I think merging InspireLord with Alchemist and peppering in a few military exploration / tactic features is the practical way to go.
LATE EDIT: Too much shifting and in-combat tactics seems to interfere with 5e's TheaterOfTheMind and QuickCombat goals. So I'm really lost on how to do a TacticalLord.
Are there any good Tactical Warlords out there to enlighten me?