In strat one good horsethrower with jarids or spears or lances can keep an entire spawn secure of cav. The accuracy also really is underrated, I've never had trouble doing longdistance shooting, maybe you should've taken some time to get used to the arch of flight, while horseranged have less damage as long as they are standing still their accuracy is exactly the same as that of someone on the ground, and the HA skill both reduces the movement and damage penalty, I can kill enemy ground throwers all the time even with these minor penalties.
When I play as a horsethrower, unless I'm about to die/get dehorsed and it is my last desperate move I'll never take a shot were I have serious negative speed bonus intending to hit the target and not just scare him off, I'll also never take a shot that has any real chance of hitting a horse unless I'm tired of chasing the guy. If your throwing weapons get scavenged by your teammates you're in bad luck, if they get scavenged by an enemy thrower all you need is to kill him and it means you got usually 2 new stacks of throwing weaponry, so you're ready to kill far more than 4 targets.