Except schools don't give acceptances before December. I don't think many schools decide whether or not to accept an applicant right after an interview. Rather, they score the applicant's interview finalizing a score for the applicant. When Dec 3rd comes by, they'll give acceptances to the best candidates. This way, if a better applicant has a later pre-Dec interview, the adcoms can bump the worse ranked/earlier interviewing candidate down into reject/waitlist territory and give an acceptance to a stronger applicant. If schools decided on who to accept right after the interview and let their seats dwindle, they might as well have rolling admissions from the beginning. Not being able to bump earlier candidates out of the acceptance pool for better applicants is like the adcom tying one hand behind their back.
Therefore, I think all pre-Dec interviewers are on equal footing. Schools will accept the applicants they like the most from this cohort with interview date being a non-issue.