No... The Norman DUKE of Sicily had a household retinue of landless knights numbering in the hundreds. By the time of the Hundred Years' War both France and England had a core army of professional troops which the levies acted as support for.
The retinue limit is much too high (as are the amount of levies) and it seems strange they don't cost any upkeep except to replenish losses, but the existence of retinues in CK2 is historically accurate.
I think this is right, I'd more like to just see the current mechanic scaled down rather than scrapped.