6) They make it so that you don’t set your own cadence.

You can pick 5.5 mph exactly if you want. However, should you ever go run outside you won’t know how fast you are going and can quickly lose pace because you are getting winded. Why are you getting winded though? You have been training on that treadmill for months. Probably because you are going too fast, then too slow and everywhere in between. Being able to set our own cadence is a skill that takes training. Training that is not provided by a treadmill.