Why not just paint the original chips with some special ink that says VOID IF TAMPERED over the RAM chips and the board? Pretty much like other hardware manufacturers do with seals or stickers, wouldn't this solve the issue?
(To be clear, I don't know either way; I'm just assuming that this was contemplated at the time because it's easier)
This is pretty clearly just them trying to block resellers that mod their boards as that removes price pressure from them. It's end user hostile, full stop.