The main difference is the chassis is ~ 10% of the cost of a desktop. It's ~ 40% (?) of the cost of a Framework, so rolling it forward (with screen, speakers, mic, keyboard, webcam etc.) saves you a fair bit more value.
I haven't checked those %s but just using them notionally.
My case was 100$ and it's housed components worth maybe 4000$ over it's lifetime, I regret not getting one with dust filters now that it's been stickerbombed and has sentimental value.
But it's definitely more percentage value in a laptop with touchpads, wifi, keyboard, battery and display over a case that's just some bent metal and if you're fancy a glass panel.
I haven't checked those %s but just using them notionally.