This presumes they would only weed out those who absolutely wouldn’t make it, but that’s not true. Some colleges weed out those who could have a 30 - 50% chance because they don’t want too many of those not making it and messing up their “great” numbers. If you were a student with a 1/3 to 1/2 chance, you’re screwed if you pick a school like that yet could have a reasonable chance if you picked somewhere else. Look at the following table and across the GPA 3.0 - 3.19 row:
https://www.aamc.org/download/321508/data/factstablea23.pdf
If the school requires a 3.4 to support someone, it could very easily be stopping some who could get in.