Yes. If they could make a tray and flap to hold the nano SIM card and still make their phone water resistant, they can engineer the phones to have user swappable batteries. They just choose not to because it is not in their interest for their customers to keep the phones longer.
That may be part of it. It's also that people like thin phones, and replaceable batteries place mechanical requirements on the phone that make it thicker.
I'm surprised this is not being used as a competitive marketing strategy. If another major company developed a phone with removable battery and still be as trustworthy as Apple, it would be great and put pressure on Apple..