True, the only issue is that AoS would again lack a sense of progression with respect to troops. Treating the elite units from the tabletop as the late game units for a TW game results in weird situations for certain armies. Needing a tier III city at minimum to recruite anything other than basic skinks & saurus as the lizardmen for example means that for the early game your army just barely functions and you can't really do anything smarter than just throwing them at your enemy. After all, all you have is basic infantry.
And that is imho the biggest drawback at using an established universe for a TW game. Fantasy stories rarely if ever have enough of a history worked out to be able to get the same sense of unit progression that you have in a historical TW game, while also Always having acces to a functional army at all times.
Though an alternative could be to use the basic mechanics the tomb kings use. They can field an infinite amount of basic skeletons, but for everything fancier they need to build a building, and having 1 of those buildings gives acces to say, 2 archer units. Having 2 buildings would give you acces to 4. And so on. Using that to give acces to elite, but core to the general strategy of the faction, units could be given even in the relative early game by just having a base-value that increases with more buildings (e.g. you need a tier IV building for more carno's but you can Always have at least 1)