That is a gross misrepresentation of the situation. Old batteries' internal resistance rises and they become unable to deliver high current. If you try, thanks to V=IR, the output voltage will droop and you'll brown out. Limiting CPU speed prevents high current draw and random device resets. The alternative was to let it run fast and have it randomly reset under load even when battery is 50% full.

All of this is only relevant cause apple devices are often used for so long after release (5-7 years, this message typed on a 5 year old iPhone) [1] (random source, more available on google.com) while statistically few android devices last long enough in consumer pockets for this to matter (2.5-3 years is average)

[1] https://www.reddit.com/r/Android/comments/9uha1o/android_vs_...