[76SlashDolphin]

Anecdotal but I bring my steam deck with a dock and M&K with me when I visit family since I don't have a desktop computer there.

Also, the Steam Deck's OS is by far the closest you can get to a traditional Linux distro since it's GNU+Linux under the hood. The built-in desktop mode is extremely close to a basic KDE Arch install, especially after you disable read-only mode. Android doesn't have as full-featured of a desktop experience unless we count Samsung DeX and even then display out is available on a vast minority of devices. iOS has no native display out and iPadOS doesn't even support normal 16:9 screens without black borders. The issue with all of the above devices is that their "desktop" modes are janky afterthoughts while on the Steam Deck it's a core feature.

[AmericanChopper]

Is a windows server a desktop PC. If not, why?

[Dylan16807]

If you daily drive it with a GUI, then it's close enough.

[AmericanChopper]

Can you think of any reasons why it may have been omitted from these statistics then?

[Macha]

Because it's derived from web browsing statistics, which is something people using it as a server and not a desktop don't do very much of