They can do it with their own machines, as the replacement I got was a refurbished one (with a different model of battery installed). My original machine was i

They can do it with their own machines, as the replacement I got was a refurbished one (with a different model of battery installed). My original machine was irreparable as the battery expansion had damaged the screen and warped the metal of the case itself! I agree they're not serviceable by mere mortals, though, and many upgrades are impossible. I have a Thinkpad X201 Tablet from 2010, and it's easy to take it apart and replace/clean bits. There's a serious cost to that, though: the entire Surface Pro 4 tablet takes up only about the volume of the Thinkpad's screen. The Thinkpad as a whole is about three times that thickness. This is only partly an age thing - mostly it's serviceability design.