I'm positive that such heavy armor (I don't mean jousting) was used in battle, and read enough in history books about such 'heavy' knights. This armor was used only for heavily armored knights on heavily armored horses, and I doubt that it is expected that every single rider would loose at least one horse in combat. Plenty of horses carried their riders through several battles, or died of their wounds after the battle and such. Death of a horse, would probably have been expected as often as the death of the human, although it common sense that the horse dies before the human it is carrying.
I'm not saying if its efficient in my oppinion or not, but I am saying that countless of sources say that this was the case, and it doesn't sound too far-fetched either if you think carefully about it. Sure the death of the horse would mean the death of the rider as well, however the horses these knights rode were fully armored in plate as well.
Like I said however, the current physics of the game suggest the the armor that players wear is relatively light, and is light enough for people to jump onto the horse in etc. So I don't understand whats the point of your argument, other than trying to prove that you are right and I am wrong. Regarding the idea, we are still saying the same thing, so this perticular discussion in my oppinion is pointless.
