Absolutely agree 100% with your concluding paragraph, particularly the importance of the things you mention. And, some colleges definitely do use the committee letter system to limit applicants - and that’s info that’s generally pretty easy to dig up if anybody cares to. But as of early 2019, of the 20 or so non-service academy colleges with the highest MD applicant acceptance rate (according to AAMC) including those mentioned by OP, not a one has any grade or test-related requirement for receiving a committee or composite letter (and a couple don’t even offer those). The only requirements involve meeting and paperwork deadlines - and if you can’t hit those, maybe you shouldn’t be applying to med school. Now, I’ll try to shut up and let folks who’ve been at the schools OP mentioned talk about their actual experiences.