A crazy take since apple has very clearly made anti-consumer moves in the past.
If having a baked in battery caused there to be 1% more iphones sales which would they choose.
You were likely nodding along when Jobs was out there telling people they were holding the phone wrong.
Replaceable batteries lets you use your phone longer, that means people will take longer to buy a new phone and reduce iphone sales. Such anti consumer moves requires regulations to be fixed, since there is no incentive for the company to be pro consumer here.
Sometimes "better phone" drives "sell more phones"
Sometimes it doesn't.