No, the remaining profiles aren't automatically added; you have to add them one at a time.
Yes, it's tedious. However, it means that you have the chance to clean up the biography and sources before adding the profile, instead of adding hundred or thousands of profiles full of GEDCOM cruft that someone then has to clean up. (I speak from experience. I still run across profiles from my initial GEDCOM import five years ago that had gone off my radar and badly need editing; it's much easier to fix the profiles as I add them.)
I also strongly recommend AGAINST using GEDCOMpare to edit profiles created by other people, at least until you've added a bunch of profiles and are familiar with what kind of editing of the biography and sources is needed. So many people use GEDCOMpare to add junk to profiles (not even good new sources and data, just crap that they don't bother to merge into the existing biography) and then leave it for the PM to clean up; don't be like them.