Again, the problem was not throttling.
Nor was it the obvious fact that Apple did not foresee that their too-small battery could fairly quickly degrade to the point that an iPhone could crash. (Otherwise they would have included throttling in iOS from the start.)
The problem was that Apple's employees repeatedly told customers that their battery was okay, and some employees suggested upgrading to a newer phone. They did this (probably innocently because Apple did not clue them in either) instead of letting the customer know that a new battery could restore their phone's speed.
True, but Apple is infamous for avoiding anything that smacks of bad PR.
Apple had bragged about their phone speed and battery life. The last thing they were going to do (unless forced to) was publicly state that they had to throttle what they had bragged about.
The only info most users saw was the upgrade notice on their iPhone:
View attachment 757061
Only those who took the time to go look at that link would've seen this slightly more detailed explanation, which still avoided any direct mention of slowdown:
View attachment 757062
Apple clearly tried to avoid any bad PR related to performance, which is understandable. It just didn't work out in the long run.