It doesn't take long at IRC for someone to start dissing SA-MP, I only mentioned the word SA-MP and a few MTA players start with the hating. To be honest, if players didn't create such a divide between the two mods, the GTA MP community would be united.
Unfortunately, MTA believes because it can do more, it should be No.1 for the players, that's rubbish. GTAIV can do more, but I don't play GTAIV, I player GTA San Andreas.
I agree with the name, if I type MTA in the address bar, I get a transportation authority website, same as the search engine, MTA Deathmatch is there, but it isn't top.
Also, MTA complicates things. I tried to get a few of my friends playing a emulated version of my racemode, but for them SA-MP was a lot easier to adapt to.
At the end of the day, MTA coding and capabilities are fantastic, the possibilities are endless..... this only appeals to coders.
SA-MP on the other hand is easy to set up, easy to play. That's why SA-MP is more popular.
A game is for the players, not the coders.