But that's most likely 1% of the market. They can have their own phones. The rest of us just want water resistance for accidental contact with water and easily replaceable batteries.
I think you’re in a techie bubble. I would wager more people care about better water resistance (for example, because they want to use their phone in the shower) than about easily replaceable batteries.
The overwhelming majority of people will never even contemplate trying to replace their own battery no matter how easy it is (unless it’s literally 90s/2000s-style snap on).
We have our own phone, it's the iPhone. I paid the money for it because I wanted the full package. You can buy your own kind of phone that's not the full package. Many different vendors are making that.
The iPhone is not waterproof, it's IP68 rated meaning it's water resistant. Swimming with your phone is absolutely not recommended and I don't know a single person that does this (unless we count people using special waterproof cases for filming).
So no, the average smartphone buyer does not swim with their phone. Manufacturers had other incentives to make changing the batteries harder and there was no pressure from customers to increase the IP rating. In fact all you hear is people ranting how much it sucks that batteries are so hard to change these days.
Is that all you hear? I don't hear that at all. People around me didn't change the battery when it was easy either. I was always like an alien when I suggested it.
I remember when the iPhone first came out non-tech friends had recurring nightmares about forgetting to take their phone out of their pocket before swimming.