Yup - as someone else pointed out I wasn’t clear in what I said. If you buy a new mobo to upgrade your laptop, you wind up with an older mobo that sits there. You can then actually use the old mobo as a desktop computer as long as it has ram and an SSD. The form factor and IO were designed with this functionality in mind.

If you upgrade the motherboard, you can actually 3d print or buy a $60 case and use the old motherboard as a desktop.

edited for clarity