In my experience, any device that requires a custom-form-factor battery is vulnerable to planned obsolescence. If you want to replace your phone's battery 10 years down the road, your OEM won't be making that model anymore; you'll need to find a compatible third-party battery, and of course you know that that means a cut-rate Chinese knockoff that is mislabeled and comes nowhere near the specs of your original.

You could hedge your bets by purchasing a replacement battery soon after purchasing your phone, but batteries have a limited shelf life, and so you'll either need to put that battery into partial service, or it'll just go spicy pillow long before you really need it.