Take a look at this study to learn more about the importance of interviews, regardless of format, when making final acceptance decisions. You will see that medical schools rate interview results and letters as more important than other data when at the final stage of review.
https://www.aamc.org/download/261106/data/aibvol11_no6.pdf
Yes, we continue to evaluate all data in the final stage and while there is no particular mathematical/weighted equation to give MMIs more power than other information, we agree with the findings of the above referenced study that the opinions of our 10 colleagues that observe you, independently, in 10 situations makes for a rather strong impression.
Each applicant in the final stage (post-interview) is assigned to a review panel of 9 committee members who EACH put forward a recommendation to the full committee. Therefore, similar to the MMIs, an applicant is evaluated, independently, from each reviewer. All scores are tallied and then the frequency of accepts/holds/rejects drives the committee-of-the-whole deliberations.
Hope this helps.