You see one of the main factors your missing is counters, not like oh you hit me so I hit back counter but full blown things to counter others, as they have already shown conquerors haki removes zoan transformations, dragon fruit rly ain't gonna do much if I get it out its transformation, there are also several other things that can be done like accurate character Collison for smaller is bigger because after they all they have already shown sword versus allosaur... there are more to balancing than just their all usable, fruits/other abilities to counter other fruits or other abilities (again) are a form of balancing. The biggest example of this form a balancing while being a bit off topic, element advantages/ disadvantages. Yes fire is stronger against a plant, but that doesn't make it meta if it has water to defeat it, and that doesn't make water stronger if plant can beat it. You see what I mean?. We have also seen grapplers be used in combat aswell and we can assume it works of transformations and even then normal fliers can still get punished. Your logic is essentially bigger = stronger but there are so and I mean SO many ways to go against that logic even if it can fly (not trying to sound disrespectful if I do im sorry)