I will give you another unrelated example to demonstrate fake obsolescence on an iPhone. For example, on the iPhone 13 Pro Max, You cannot set the battery to stop charging at 80%. You can do this with the new iPhone. I don't remember either 14 or 15, but you can't do this with the 13 Pro Max. So can you say that the iPhone 13 Promax is actually supported for so many years with the latest and greatest iOS When apple doesn't actually bring these new features. Back to the older version of iPhone?

FYI, you can get most of the same effect on your 13 Pro Max by plugging your charger into a smart plug, and using Shortcuts to make an automation that turns off the smart plug whenever the phone battery goes about 80%.

I use that on my 10th generation iPad and used it on the iPhone X that I had up until about two months ago when it got replaced with a 15 which does support the "charge to 80%" option. It works great.

The only minor annoyance I ran into was that the phones where the OS supports the 80% limit it will occasionally go to 100%, which they say is necessary to keep the battery level indicator calibrated. With the smart plug method you'll have to handle occasionally disabling the shortcut (or charging with the charger plugged straight into the outlet).

Just make sure to pick a smart plug that can be turned off from Shortcuts.

By default all iPhones stop charging at 80%

The "stop at 80%" option is 15 and later.

I think you are thinking of the "optimized charging" option, which tries to guess how long you will be leaving the phone on the charger and then pauses when it reaches 80% until it gets near the time it thinks you are going to take the phone off the charger and then charges up to 100%.