I know of some programs that are about equal path and Derm trained. I also know of several that are Derm trained heavy. Can't say I know of any that are path trained heavy. That's not to say they're not out there.
I think program directors really try to pick the best candidate regardless of training. However, as someone mentioned, Derm trained often have more impressive baseline stats/apps.
Another thing to consider: As also mentioned, dermpath job market is sorta tight right now. Program directors want to see their trainees get jobs without problems. It's likely easier for a Derm trained person to get a job. I just started my last year of Derm, and I get emails from Derm job recruiters about 3 or 4 times a week. After my fellowship training, if I don't land a full time dermpath gig, I shouldn't have a problem getting at least a Derm clinic job with hopefully dermpath sign out part of the time (what I actually want to start out with anyway). If a path trained person doesn't find a dermpath job, is it equally as easy for them to land something path related?