Employers that reject applicants because they started at community college before completing a BA/BS at a university

This part is well established in several sectors. And this part is entirely reasonable:

It is this part where the train goes off the track:

Mixing grads of “low ranking” unis (eg not inside the T25-T50 cutoff noted earlier) with students who started at community college and then finished at a T25-T50 is a false equivalency. It might not be fair to the star student at the ‘low ranking’ uni, but the OP’s point is that they have to draw the line somewhere, and as another poster put it ‘fishing where the fish are’ makes sense.

On the other hand, to then argue that a student who did 2 years at Duchess County Community College before transferring to Cornell and graduating with a 3.8 GPA in Math (or whatever) from Cornell, is inherently so much less likely to be a good recruit (esp in the key areas noted of ‘strong mathematical background and critical thinking’) than a student who did all 4 years at Cornell that they should be eliminated a priori is not logically defensible.