I'm not sure if various government agencies and big businesses around the world running enterprise Linux desktops from companies like Red Hat and SUSE would agree though. They're a small slice of the pie, but that doesn't make them any less serious. Feel free to disagree if that makes you happy.
Those aren't desktops, they're workstations. Learn the difference.
Not to mention most business/government machines ARE desktops, usually using an onboard video solution to boot. A workstation is generally regarded as a heavy-lifting unit designed for a specific task, such as A/V editing, 3D ani. And usually on specifically non-server and non-desktop boards.