It was a pretty terrible controversy at the time but I think the battery health settings pane we got out of it was a good compromise and a net positive. What would be even better would be fully user-replaceable batteries.

To be more precise, the phones weren’t slowed down to keep the batteries from failing, they were slowed down to maintain stability and stop random crashes. As batteries age they lose their peak voltage capability, so you’re basically undervolting your components unless you slow them down.