Good thing that Apple is _very_ concerned about environment and the reduction of the electronics waste...
+No need to tell me you replaced yours. So did I. I still bet >90% of units are not replaced.
https://www.ifixit.com/Teardown/MacBook+Pro+13-Inch+Touch+Ba...
It does, but it might be the least wasteful way to do it.
Manufacturing a modular machine is more costly than a single integrated board. If almost nobody exploits the modularity then all those connectors are wasted. A few million unneeded connectors traded off against a few hundred upgraded laptops is not a good deal.
I like upgradability, but most people don't care, and the economics and environmental impact are dominated by most people.