Zardnaar
Legend
Have you listened to the Mike Mearls podcast that re-ignited this discussion? He addresses the point you're getting at. And, bottom line, yeah, it can be OP, and yeah, that level of OP is w/in the broad margin for error to which 5e is balanced (if you can call that balanced).
Actually, a lot of 5e critters have /tons/ of hps - the ones that noticeably lower hps are de-facto minions, or sub-minions when hit with AE save:1/2 damage that ganks them on a successful save. But, that aside, the 4e Rogue had 2d /to start/, and any striker and not a few fighters could be a great target for action granting.
What really made Commander's Strike more tactically interesting and merely good than go-to-optimal in combination was the Rogue. In 4e, at release, mind you, the Rogue's Basic Attack wouldn't keep up as you leveled, because there was no Melee Training Feat yet, and, his SA was 1/round. So he was only a good target for Commander's Strike when he hadn't been able to get in an SA, and was behind the damage curve, the Warlord would then give him a chance to get back on track - exactly a leader thang.
Design elegance at work, really.
But while 5e is inelegant in the name of natural language & classic feel, that just makes it more complicated, not gimped.
5e could totally handle anything the Warlord did in 4e. Some of it might be a little trickier to design, or take three sentences instead of two words to explain, but that added complexity is just in the nature of 5e.
Abject nonsense. The Warlord challenged paleo-D&D's One True Way. The Band-Aid cleric and meatshield fighter and LFQW.
The 4e warlord absolutely has to be fit to 5e design. 5e design is less balanced and unconstrained by Role, the Warlord needs to be adapted to that. It needs to be powered up to the degree that the Bard, Cleric, and Druid were from their 4e 'Leader'-role versions. And, it needs to be expanded to fill the whole range of archetypes the concept suggests, which should include what would have been game-breaking intrusion into the controller role in 4e.
The fighter needs to take some of that same medicine.
You could, it would just be radically underpowered and non-viable compared to a Cleric, Bard, Druid or Paladin.
I think most of the 4E stuff is fine with the exception of the at will attack granting.
Some of my homebrew Warlord stuff is more powerful than the 4E stuff. +2 to hit becomes advantage that sort of thing. Mucking around with WL healing rates is also tricky I have revised inspiring word about 5 times (bonus action 1d6+ allows HD used, bonus action bonus hit dice, bonus action 1d8+ ability mod, bonus action +2d6 hp, and how many you get and how it scales).