That was before flagship phones needed to become thinner and bigger every few months. Can't have commonality of parts if your six months old battery is thicker

That was before flagship phones needed to become thinner and bigger every few months. Can't have commonality of parts if your six months old battery is thicker than the whole new phone. (There's still plenty of phones with replaceable, more-or-less standardized batteries available… but it's $50-200 phones that nobody wants to buy because they're not sexy enough. Even though they've been fast enough for years…)