I mean, if it's "easily gameable", why doesn't everybody just game it? There exist real score differences in practice.
You can say that it's "gameable" in response to time and resources spent studying, but that's actual learning, so of course that would result in higher scores.
It's one thing to say "Some people don't have enough time/resources", but it's another to pretend that these tests carry no signal.
Studying for how to game the SATs is not actual learning, in the sense of being generalizable knowledge or skills. It is learning how to game the exam.
It is also incredibly time and resource dependent, as you have surmised. Guess which strata of society tends to come out on top in that environment?
You can say that it's "gameable" in response to time and resources spent studying, but that's actual learning, so of course that would result in higher scores.
It's one thing to say "Some people don't have enough time/resources", but it's another to pretend that these tests carry no signal.