Well I have virtualized DC’s for companies with size ranging from 8000 user base and (43000 objects) to 120,000 user base (250,000) objects spanning over 130 countries across the world using both VMware and Ms Hyper V.
Virtualizing the DC’s , gives more flexibility and reduced cost and better DR plan. It gave my design a very robust continuity that I was tempted to not include backup but i did. With Virtualization, I was able to automate most task. For example , in an event of power loss, i could set the order I want my servers to start up first. Like the DC’s before any other servers without manual intervention( cant archieve that on physical servers). Then also High availability provided by Virtualization and DRS.
When it comes to timing that is experinced due to lapses on host machine, all dc relied on the same external time source.
This is a tried and tested design and I have been implementing such since 2006. My client with a totally vrtualized DC includes the biggest bank in the world, one of the biggest electronic company in europe (specific Holland) , The biggest Travel and money exchange company to name a few.
I do not understand peoples argument except for lack of knowledge or laziness.