Imagine if, to avoid damage to engine parts, engines would keep their heat limits in safe zones to not blow up when friction goes up. Imagine if, when you don't tune up your car, it starts running, factually, with less horsepower.

You do lose X horsepower every 1000 miles. You get it back with your tuneup. Which involves changing the oil.

You lose X MHz every Y% of battery discharge capacity lost. You get it back with your tuneup. Which involves changing the battery.

You don't need to detune maliciously to get the effect Apple is getting here. The system just needs to self-calibrate to a depleting battery... Which is super good for the battery because it won't actually get worse as fast. Discharge cycles, especially close to the discharge limit, puts strain on cells, which have voltage sag closer to end of life.