...although, at least as far as the light nomadic-pattern HAs go, arguably the main reason for their continued use throughout the millenia was simply that whatever their real and numerous enough limitations, in certain parts of Eurasia where cavalry was the king anyway they were just plain readily and cheaply available. The common nomadic tribesman could be employed as a quite effective light cavalryman, scout, raider and skirmisher "off the shelf" without further ado.

Given the vital importance of light horse for what might be termed "campaign duties" (ie. scouting, foraging etc.) for any army, whatever their battlefield potential, this was obviously a detail any warlord could well appreciate.

(PS: What, no Almighty Moustache(tm) ? You're slipping, TPC. )