There are a ton of things to be upset at Apple for, but as someone who would never consider owning an iPhone I do understand where they were coming from. The problem was the aging batteries no longer being able to source sufficient current to run the processor at full speed. Since the batteries in iPhones are nearly impossible to replace this meant the phones would crash whenever performing a demanding task leaving much of the battery capacity unusable and the phone e-waste. By throttling the processor they reduced the current peaks and allowed these phones to continue operating.
My Moto G4 had the exact same thing happen, but without a software update to throttle the phone and hide the issue from me it started to crash all the time. I simply replaced the battery, but for most people the only option in this case would be to buy a new phone.
Apple probably should have made it an option even if enabled by default on phones with aged batteries. That way you'd need to acknowledge the risk of running at full speed again and not be upset when the inevitable crashes come. Of course Apple being Apple they refused to give the consumer the option so simply throttled them all.
Despite the outcry claiming the opposite, I'd bet that decision significantly reduced the amount of phone waste from non tech savvy consumers.
