>a good linux admin can support many small companies remotely
No they can not. They quickly get bogged down in minutiae (like broken fax machines or non-working VoIP), get disgusted and then quit their job.
Having separate 'low level' admins is not really an option with Linux because these admins won't be able to do anything complicated. And doing back-and-forth between two departments leads only to frustration and pain. It's much easier for businesses to pay a couple of thousands dollars and get a Windows Server.
Guys, I'm speaking from a (bitter) personal experience of actual migrations. You're offering me basically anecdotes in the form of: "But my organization works fine! See, our employees are kernel developers and compile their own desktops from individual molecules using 3D-printers! So this workflow can definitely work for all Mom&Pop companies with 2 employees!"