You also have to consider that grades can often be handled very subjectively and the vast majority of high-school teachers are left-wing, with a large proportion of them far-left (multiple studies have clearly shown this). Do you think that in the current climate black, gay, transgender or other 'special' cases are going to get a completely fair score or are they likely to get softer assessment and padded grades? In many places, student-teacher relationships (affinity, bias, etc. not sex you smutty devil) can have a major impact on grades received. Even with a teacher that tries to avoid it, this bias can show, and we know far-left teachers will be embracing it.

Also, while it may be hard for a single teacher, or even two or three to boost your GPA dramatically, they can do huge damage to high-performing students they don't like (say, straight white males).