Yes, your point about the drop rate is important here. One change that a lot of universities have made recently is prioritizing more flexibility in individual students’ curricular choices.
Gone are the days when, for example, all entering first-year students got automatically enrolled in Freshman Composition and College Math 101, or whatever, and then had to sink or swim in it that same term, irrespective of personal preference. Automated enrollment processing has allowed a lot more real-time maneuverability in students’ course choices.
Thus a lot more students nowadays are able to avoid sub-A grades in a course they’re not ready for, simply because they were able to get out in time.