High school _could_ become such a filter if a national standard were developed and _enforced_. Education shouldn't stop until that is met or someone ends up on mental disability status. More help still should be provided if the external environment isn't conducive to success.
Such a basic qualifying education should be a human right, further the right of anything which can think. Graduation from that filter could be a requirement to being a productive and full member of society. I _still_ disagree, that under the exact circumstances outlined above, where the right to that education and the fulfillment of it's mandate are a per-requisite, in that set of circumstances graduating could be a requirement to vote. Proof that someone is a functioning member of society (because otherwise they'd be a pre-adult protected class of society).
The SAT provides a hard deadline which prevents you from de-escalating high school.
College provides a soft deadline which prevents you from de-escalating as getting a degree before you run out of money is an employment filter.
You have to remove college as an employment filter in order to de-escalate the whole thing.