This is my opinion- please note this is NOT a fact:
Scientists label planets and dwarf planets to further distinguish what actually classifies a planet. If scientists didn’t have a classification system, the argument could be made that solid matter in space could be named a “planet” (asteroids, moons, etc.). Having certain classification thresholds means that planets that could support life are identified.
Again- this is NOT fact, my simple opinion. I could be very wrong.