Replaceable batteries were superseded by batteries of sufficient capacity for 99% of users. (And for the remaining 1% I'm sure the non-Apple marketplace has fantastic, no-compromise solutions.) Remember when it was impressive for a laptop to have three real hours of productive battery life? Back then, most laptop batteries were trivially hot-swappable. Now it's normal to get eight or more hours of productive use from a laptop battery.

I realise that capacity is theoretically orthogonal to swappability, but functionally it's relevant because battery casings, compartments, connectors and chassis strengthening elements all take up space that could otherwise go to a larger battery pack.