If WotC published "D&D: Romantic Fantasy" as a rules module with support for inspiration tropes, and then made a Warlord which fit with those tropes, that would be fine. There are already existing rules modules in 5E for resting variants, spell points vs. slots, combat options, initiative systems, etc. This would be the first rules module that had a full class designed specifically to interact with the rules module, but that isn't terrible.
Those who don't want the rules module could just not use it. That's a big improvement over having a class in the core game which relies on implicit optional rules--the optional rules are instead made explicit first, in the rules module, and the class leverages them. E.g. "The Warlord can Exhort as a bonus action." "The Warlord adds his proficiency bonus when Inspiring, and can Inspire two targets simultaneously when he reaches sixth level." Etc.