It’s design for manufacturing, not design for repair. There are tradeoffs everywhere in hardware design. I’m guessing that by building the MacBook this way they

It’s design for manufacturing, not design for repair. There are tradeoffs everywhere in hardware design. I’m guessing that by building the MacBook this way they greatly increase the rigidity of the keyboard. If instead they had made the keyboard a separate module in order to facilitate easy replacement then it’d either be way less rigid or it would need an additional backing plate which would increase the overall thickness of the computer.