I have both android tablets and an iPad from 2014 and the ipad still feels like a modern device with the latest OS version while the android tablets are stuck on a 2015 build of android and feel very slow.
I bought an iphone 12 this year because my iphone 6s+ is 5 years old at this point, and I wanted to spoil myself. My new phone feels basically identical to my old phone, and despite 5 years of innovation I think it was a waste of money. Most of the improvements in iphones in the last 5 years has been in software, and the 6s (for now) still gets all the updates anyway.
There's some differences - low light photography is much better. My new phone is also physically smaller with the same screen size and much snappier. But its also missing a headphone jack, force touch and it can't be unlocked with a face mask.
I think next time I'll keep my phone until it dies - which I'm hoping will be ~6-7 years. Given that sort of longevity, the price seems pretty reasonable.
Yes, the SoC gets improved each year, but so does their ability to manufacture, i.e. the manufacturing costs should go down, and they keep spending the same amount on R&D to innovate. Economies of scale also play its part.