If the battery was user replaceable, how would that improve the issue? If anything, it would make it worse from the standpoint of Apple’s customers getting a subpar product.
Batteries are the worst possible offender when it comes to counterfeits. If you’re not getting them straight from the source, it’s basically the wild west. I don’t order them online any more because it’s a 50/50 chance of getting a significantly worse product, even from reputable vendors (ahem amazon)
I think Apple is nudging their consumers towards getting an official replacement and honestly it makes perfect sense why they would do that in light of the market offerings.
Imagine an iPhone with a user replaceable battery. 30% of customers are gonna order the replacement from Apple anyway. 20% are going to order a mid high priced good battery from Anker. And 50% are gonna get swindled by an Alibaba drop shipper. The end result: the iPhone winds up behaving like a commodity android phone to the consumer.