Posted below for posterity, not necessarily you.
The reddit post: https://www.reddit.com/r/iphone/comments/7inu45/psa_iphone_s...
Finally, from the horses mouth:https://support.apple.com/en-us/HT208387
"iOS 11.3 and later improve this performance management feature"
and
"iPhone 8 and later use a more advanced hardware and software ..[snip].. As a result, the impacts of performance management may be less noticeable on iPhone 8 and later."
My conclusion: It is true that Apple was only targeting phones with dodgy(to a degree of approximation) batteries.
OTOH, Apple does a better job now. Both in execution and communication.
Whether Apple would have reached this achievement without batterygate is unknowable.
My apologies for spreading misinformation, thank you for your patience.
Edit:snipped some bits for conciseness.
Sorry to be nitpicky, but this is actually not the case.
The whole reason this was initially discovered was because someone on reddit ran Geekbench before and after a battery replacement and got a huge performance increase. Not telling users is inexcusable, but phones where the battery was fully functional continued to run at full speed regardless of age.
> You still can't trust them
On this point I 100% agree!