I would clarify only that it's impossible to replicate with the officially published extant classes of 5e; it would be trivial to design a class within 5e's chassis that hits the "Dex based heavy weapon user with good AC" standard. Replicating the oath mechanic that made avengers want to attack isolated targets, and replicating the amount of movement abilities they had, would be somewhat more challenging.
Ah, yeah you're right. That was sloppy wording on my part. The Oaths of Enmity would be tricky but not impossible to homebrew, the rest is totally feasible. It just doesn't exist as an implemented thing and is, sadly, unlikely to be.
Shows one of the ways in which the "class, subclass,
à la carte multiclass" model can stumble. If your idea requires blending bits from
at most two classes, you're fine. If it requires
three you're kind of screwed in official 5e. Paladin+Rogue+Barb is rough. Or the "more than just a jack of all trades" Bard, who really wants levels in Cleric, Rogue, and Warlock. Or my "storyteller Paladin" concept from 4e, that would require Bard and probably Sorcerer levels to work in 5e.
The irony being, this sort of thing is what
à la carte mutliclassing is supposed to be great at, but because it means sinking more than half the usual levels of a game (e.g. level 6+ out of no more than 11 for most games) into just
unlocking the features, the strengths of the tool become weaknesses.