We understand what you are saying has been said the same way for 8 years I have read this site. However, there are tons of nuances that some MD students don't understand about DO schools. Yes, it is true that overall standards for DOs schools is lower than MD school, more specifically clinical education. However, MD school are not that similar in there rotations and there a few MD school rotations that are mostly preceptor based. There are also some DO schools that have the vast majority of their rotations with residents. So there is an overlap with the quality level. There were some MD students who also argue that DO schools have worse medical students because they accept people with lower grades and lower MCAT scores. This doesn't speak as to why student from schools with 26 MCAT scores such as Morehouse are treated better. On the opposite side, there are now DO schools who bolster MCAT and GPAs similar to some MD schools. You may argue grade replacement, but that is gone...
We also understand the situation with lower tier MD schools (a few MD students are in denial of this bias happening, I've seen this also through the years). When you look at Harvards match list with all the MGH, BWH, Hopkin's etc. matches with the classes having a USMLE of 240, it can get nauseating (since you know these students are matching into top quality residencies with a < 240). And I'm pretty sure there are MD students from mid-tier schools actually have just as good research and experiences as the ones from top-tier schools, yet their not picked for top-tier residencies.
I think the point I'm trying to get at here is that these are all justifications used by people in positions of power to weed people out. There is some true to it, but not as much as they make it out to be. When a PD at a top program has all these impressive applicants, they will use whatever means to weed them out. Even if it means weeding people from out of non-US schools, DOs, or even low-tier MD schools with a simple filter on the ERAS program.
EDIT MADE