I think that model is discontinued. You need to compare with the X1 Carbon models.
Only things missing are the RAM on a 13" version and wifi cards being soldered in (but you can theoretically use a different wi-fi card on a 17" as it has a spare M.2 slot).
Before that I've performed upgrades from XPS 15 9550 to 9560 and 9570 by swapping the motherboard and couple other parts. So it's not like Apple _at all_. It's more like the opposite of Apple