I dunno, my wife has has the same iPhone 11 Pro Max since 2020. She had to get the battery replaced once at an Apple store, which I believe cost $99, and it took like thirty minutes and it wasn't that hard.

I'll admit it's a little annoying that I have to pay a hundred bucks to get the battery replaced, but the phone is otherwise fine and still gets updates, so I don't know that I buy that it's "planned obsolescence".

It's planned obsolescence through price. Your wife paid >50% of the phone's value just to replace the battery. Many people won't think that's worth it. It could have been a $30 user replaceable battery.

Imagine you can order a battery from Apple for $20 and you swap it in 1 minute: less money, less time, user satisfaction++.