For all intents and purposes, yes. And to be frank I don't think thoughts seem to be all over the place; there seems to be a succinct consensus that it simply just does help a lot to go to a top undergrad (my experience talking to MSTP program directors at schools similar to mine, maybe not for MD but I assume this is the same).
For the instance with the panel. they explained the academic grading system and evaluation of prestige after a student asked if "going to our university gave an advantage in the process and could make up for a GPA." I remember they gave us the 0-2 explanation (verbally) then rambled about how a very high GPA at colleges filled with top students (aka just a top university) was much more impressive than the latter at a 'normal' university, but that if you bombed at a top university you would be in a bad position. The scale was 0-2 with 0 being unranked or noname, 1 being just a decent university, and 2 being the big names.
I know grade inflation, deflation, etc. exists at these schools, but it's really pointless to debate the legitimacy or logistics of that. At the end of the day, people working at top programs just favor people who attend top programs. I mean hell, go look at any dean/MD/MSTP director's alma mater and tell me that there's no BS going on....it's just overwhelming.