For the majority of Android phones, two to three years was also the length of time you got software updates of you bought the phone right when it was released, if you were lucky. I would have loved to pay somebody 80 EUR to replace the battery in my Samsung S10, but that wasn't an option since it was EOL.
Upgrading a phone also doesn't mean that the old phone goes to the bin or the new phone wasn't used before. Lots of people upgrade from one hand-me-down phone to another, others buy on the secondary market. Longer software support also extends the lifetime and viability of that market.
Sure, eventually the battery dies and the screen breaks. For many devices it's cost-effective to have somebody repair it. Having user serviceable batteries would make it much easier still.
Upgrading a phone also doesn't mean that the old phone goes to the bin or the new phone wasn't used before. Lots of people upgrade from one hand-me-down phone to another, others buy on the secondary market. Longer software support also extends the lifetime and viability of that market.
Sure, eventually the battery dies and the screen breaks. For many devices it's cost-effective to have somebody repair it. Having user serviceable batteries would make it much easier still.