Reasonable minds can agree to disagree. The technology has been there for larger batteries, 120 Hz displays (why does the iPad Pro have a 120 Hz display but the iPhone does not?), always on displays, under-display fingerprint sensors, hole-punch front-facing cameras, more RAM, and so on. It's been there for YEARS. Samsung S21 is a good example of what I'm talking about.
You admitted that technological advancements on Apple iPhone devices (besides the A-series chip) happen at a rather slow pace, so we can certainly agree on that. Where we disagree is the motivation behind the rather slow pace. You claim that Apple is cautious since it sells 100 million devices, therefore it moves more slowly. I posit that improvements on iPhone happen at just a fast and slow enough pace (i.e., Goldilocks zone) to maximize the incentive for users to upgrade yearly. It's in Apple's best interest for users to upgrade year after year... Think about it. If Apple released 120 Hz displays and 8 GB of RAM on the iPhone 12, what would be the point of getting the 13? Samsung and others have been using 120 Hz displays for a while now. All that being said I know many users don't upgrade every year and that's why Apple is getting into generating revenue by offering services such as iCloud, Arcade, Apple Card, etc.
Nonetheless, you can't tell me that Apple isn't trying the best it can to incent users to upgrade as often as possible. Whether or not it's working is a separate argument...