You're right to a degree. There's not a huge difference in ability between someone with a 170 and 172, a 168 and a 170, or a 159 and 161, even though those small gaps have a major impact on the school you can get into. But I would bet in most cases, someone with a 144 LSAT (and there are many such people) won't do as well in law school as someone with a 170.
I don't know that either in and of themselves are a predictor of law school success. I think it is about the thinking/study/reading skills and endurance that got you there. All pretty easy so far? It's a crapshoot. Had to work hard and had success - better odds