This is absolute BS. What IT department is going to allow an employee to bring in their PC? How are they to know that the machine is patched, has the correct virus version installed and would let a foreign machine join the domain. Joining a PC to AD is a two step process, to do the same with a MAC requires a lot of hurdles to jump through. What about malware? I'm sure in this author's world you can just hook up a MAC to the network and everything is peachy; it is not.
I'm sure my IT department would love to have to add another device to support. It was bad enough when the users wanted us to supply them with Iphones, since they're issued phones to I don't know, make phone calls and be available when on call. You can do that with any phone. I told the idiot to do a cost benefit analysis and that was the last I heard of it.
And there you have it, it is all about the IT guys not wanting to switch, they can be absolute tyrants.