I have an iPhone 6s on an iOS 10 version which is an earlier version than the throttled one. It has 63% health. It works perfectly. Nothing else to say.
My 6s died on ios 9 well before 1% battery for example, sometimes on 20% or above, had the phone for well over 3 years on ios 9 before going straight to ios 11, when i updated the phone did get a bit throttled but this never happened again.
Same thing happened with my 4s which never got this battery management throttle.
I have never seen how much battery life the 6s had but i can image it was really bad plus the battery itself or the manufacturer made one battery that wasnt maybe the best one.
My xs max with 4 years is holding quite well, it does exhibit the same symptom of not turning off after getting to 1% but this happens when it gets to 5% ish. Now this ONLY happens when the feature is deactivated (i manually did it). When it is not activated it doesnt happen. Btw when the feature is deactivated, the phone absolutely throttled heavily starting 10% (probably due to the battery not able to hold up)
Funny thing is i havent noticed any performance diference between this on and off. I have updated straight from ios 12 to ios 14 and i did notice a bit of impact to the battery but nothing to heavy, the worst happened after ios 15 and ios 16. Both on battery and performance, though at the time of updating the battery was on 70% territory.
I can imagine people think that apple does this straight to f*** with the user and make them buy. Which i think it is true and not true at the same time. The implementation of this throttle is definitely pro consumer an this didnt activate to me until well over 3 years of use, so it does help to maintain the iphone, on my xs max i havent seen any impact on the experience itself, which ios 15 and ios 16 have actually impacted.
It is expected that new ios version impact the use of the SoC and so the use of battery, people like to recall the steve jobs era but never has my iphone aged so badly like the 4s did(iphone 4 didnt even make it past 2 os updates btw). And ios 7 absolutely ripped it. This has been different since my 6s and the now later xs max. It holds up fantastically giving the fact that its over 5 years old SoC (though in possession 4 years 4 months).
Now the fact that batteries degrade over time and arent able to deliver peak performance as before, sum that with the throttle feature, and the fact that official battery replacements are not cheap (and at least in europe are now even more expensive) is beneficial to apple and makes people replace phones with new ones which is not pro consumer.