My issue with startups like these is that they rarely have a future in which you can buy another component. 6 years down the road, when I might want to swap a part, will they even be around anymore? Or support the old models? If they do, the total upgrade price for those parts still won't be able to compete with a second hand ThinkPad.

This has been tried with smartphones too but the market is evolving too fast for it to make sense to have modular hardware.