Maybe, but if all your teachers have obvious biases and they grade on how well you pander to their biases, and all their biases just happen to line up, then you're left only able to argue one side of things.

It's not hard to imagine going to a liberal arts college where the professors are all moderately to aggressively liberal and/or Democrat.

I'm not saying that it's RIGHT that this could happen, but that it's not unreasonable to expect that it COULD happen.