It’s not that confusing. The Activision deal almost didn’t happen following all of the scrutiny Microsoft received from their earlier buying of Bethesda and making all of their new games Xbox exclusives. They squeaked by and sealed the deal in the end, but presumably they don’t want Activision to be their last acquisition ever. To that end, they’re third-partying some of their high-profile-but-probably-not-big-earner games so that when some regulatory agency tries to make that same argument for their next big purchase, they can point at the few titles they published on other consoles as proof that they promise not to be anticompetitive.
During Cerny’s presentation, he specifically talked about the compromise between 60fps performance mode and 30fps graphics modes, so it’s to get 60 fps that people are typically enabling performance mode for.