If they don't agree with the hole in the other theories which use DM to reconcile observations, thats an issue worth exploring. If they just don't like the DM label on those holes, its a fine point. What do you want to call the emerging shape in theory which is a hole, in otherwise very fine, testable propositions?

Indeed. That's why claiming that dark matter exists OR not exists is wrong. We do not know. The consensus is that it's more likely that it does.