SA-MP supports the whole model? because the models works like a single player mod, it modify's the gta3.img. U need to download a pack, unzip,copy,paste,replace and bla bla bla...
It's the same to you and a player have the same skin installed in yours GTA's. And you can do that on MTA too... (But it's very dumb)
Since mta does everything automatically and doesn't need a single game restart to change the models.
Lolz, mta is mta, sa-mp is sa-mp, how hard is to people understand the difference? @_@