Your first pickup truck analogy was bad. If SL is the Toyota pickup truck, and that is the ONLY pickup truck, then it cannot be outclassed by every other pickup truck, because there are no other trucks. If there used to be a other pickup trucks, but they all broke down or their companies went bankrupt because no one buyed them, then the Toyota SL was indeed, the best pickup truck.
Also, saying that if combined a bunch of modern games, they would be better than SL makes no sense, because no one is making that imaginary Frankenstein game, and you dont know if it would work, for a million reasons. There are a lot of things to complain about in SL, but give credit where credit is due, amongst the user created virtual worlds, SL is seems to be, so far, the one has worked best.