“ So now classes will be filled with underachieving and undeserving youth who grew up in families that eschewed homework and study?”
No.
That would be reflected if they only looked at GPA.
GPA can reflect socialization more than intelligence and ability.
SAT is pure intellectual ability.
SAT used to be more of an IQ test (when it was a Standardized Aptitude Test) but now it isn’t (it’s now a Standardized Achievement Test).
The point now is that it’s the only thing we have left, other than AP tests, that is STANDARDIZED. Every student in the world takes the same test the same day.