A chassis is 10% of the cost of the laptop. Reusable chassis just to put new hardware in isn’t something the average consumer is interested in.
Also, buying a new mainboard every few years and putting the old mainboard on a shelf is a lot less sustainable than buying a complete new laptop and selling your old laptop to someone.
Also, buying a new mainboard every few years and putting the old mainboard on a shelf is a lot less sustainable than buying a complete new laptop and selling your old laptop to someone.