There nothing stupid about controlling for circumstances.
As an analogy, let’s say you want to build a fun race car that you can take to the track. You go out and look at a bunch of used cars and you want to be qualitative so you measure out their 0-60 times.
You could just say “the car with the best time wins” and take the fastest one you tested. Or you could consider context like “this one had bald tires tha could easily be upgraded” or “we tested this one going uphill”.
The goal is to find the car that can be turned into the fastest and not which has the best numbers right now.
Better circumstance do create better students though. And all this will do is cause the best students to hide in shit schools to game the system