Technical reasons certainly play a part in it. Thin and light and high performance is objectively harder with the currend SODIMM arrangement for replacable RAM.

Technical reasons certainly play a part in it. Thin and light and high performance is objectively harder with the currend SODIMM arrangement for replacable RAM. And it's not a slam-dunk win for the laptop manufacturers financially either, because it makes their manufacturing output less fungible for them as well. If they misestimate the demand for one particular configuration that loses them money.