Quote Originally Posted by Tellos Athenaios
As for the second one: Greeks were at the time involved in quite a few struggles: Sicilian Greeks fought against Epeiros & Carthage, Mainland Italian Greeks fought in the service of Epeiros against Rome, Greeks & Carthage, and on the Greek Mainland + Carthaginians relied on mercenary armies (a small Carthaginian population controlling a vast amount of territory + the need for loyal soldiers...), and therefore couldn't simply 'replace/retrain' units like the Romans could - a whole different type of warfare altogether...
Exactly, so from a game balance perspective, cost and available manpower is the main barrier to recruitment. Since you are limited in the number of troops you can raise in a turn, cost is the real barrier to the size of the armies you can raise. Early Romans weren't that good of soldiers, but they could field and re-field large armies even in the face of total disaster like Cannae (which was arguably worse than Adrianople, but with a different aftermath).