The current approach to deal with the remedial situation you describe is “corequisite support.” In the case where the placement test says you’re not up-to-speed

The current approach to deal with the remedial situation you describe is “corequisite support.” In the case where the placement test says you’re not up-to-speed, you get assigned to extra sections of prep/tutoring rather than being told to stop your college progress and retake the prerequisite(s).