Why does what they did back then change with regard to what's going on between Microsoft and Apple now? "Well those other guys did it too!" isn't a defense.
Corporate didn't run from sole-source hardware then, in fact corporate gravitated towards it. Now you say that's a reason for corporate not to use it, probably just because it has the Apple name, a brand with which you have no experience.
BTW, lock-down is so incredibly easy on a Mac. I set my kid up on mine and the parental controls allowed me to easily control exactly what she can and can't do, down to which applications she can run, what preferences she can change, what sites she can visit, when she can visit, how long she can use the computer, etc., and it's all logged. Sweet. And that's just what's available through the UI on the desktop version.