It's not incompatible, many people in order to do research have to gain a great expertise in a thing. Others can get a Ph.D. having really no expertise at all, but just the ability to get through a research program. Others still can be experts and unable to navigate a research program due to how capricious and political they are. So the pretense is that the Ph.D. is a marker of expertise. It's correlated with expertise, but the actual thing it signals is you've gotten through a research program.