You keep parroting the term “planned obsolescence” over and over again in every comment but I do not think you understand what it actually means. Planned obsolescence is when the device becomes useless after a given amount of time. So to use the battery example, arguably a phone that ends up misbehaving or shutting down unexpectedly due to a failing battery without any mitigations is “useless” — it ceases to function as a useful phone or emergency device if that happens.
That’s not a trait specific to iPhones though — the same thing will happen on most battery-powered devices these days. It’s just that someone decided to pick a fight with Apple about it, hence a lawsuit was born. There’s nothing remarkable about this case otherwise — it could have just as easily been any other phone manufacturer.
In this example, the mitigation Apple chose (and admittedly very badly communicated at the time) was to reduce the frequency with which these shutdowns happen by dropping peak performance a bit and reducing the peak power draw as a result. That action actually prolonged the device’s “usefulness” for its intended purpose as a phone and emergency device, even if it negatively affected auxiliary functions.
In any case, if the phone slows down a bit, you might think “okay, it may be time to replace the phone soon” and you like to use this as your excuse for it being planned obsolescence. What you’re conveniently ignoring is that if the phone shuts down at random, you are probably going to think “well, damn, I need to replace the phone _now_” because a non-technical person will not likely to draw the conclusion that the battery was at fault, they’re much more likely to believe there’s a much deeper and unfixable fault.
Finally, while the batteries indeed are not user-replaceable, they are still replaceable. Any Apple Store will do it for you (many even on a walk-in basis) and it’s not even expensive to have done. Many other third-party shops and service centres also have the capability to do the same.