People don't change batteries in their phones now because they'd need a heat gun and a soldering iron and they'd have even chances of starting a fire, breaking the phone, or succeeding in changing the battery without prior experience using those tools. A shop could do it reliably, but the shop will charge 100€ because it's time-consuming and error-prone. A 3-5 year old phone is often not worth 100€.
When a battery change costs 25€ and takes 5 minutes, people will do it all the time even if they don't know that today.