As with everything Apple there is method on the madness. By beginning such a VRR they save battery. This means they can put a smaller battery in the phone and increase their bottom lines.

Pretty much all Apple R&D is about protecting their profit margins rather than benefiting the customer. On-device AI means less data centre costs. More efficient processors means less ram per device. And increases in power efficiency mean keeping the same battery as last year.

You only have to look at all the power efficiencies they've put into the Apple Watch over the years to maintain the same quotes 18 hour battery. Had they put a bigger one on as well it would last damn nearly a week!