>So you want to deny that there are people who are just inefficient?

He's offering a different perspective on what the problem might be. If your default view is that these people are "inefficient", you're probably going to be a terrible manager.

>The OP made clear that the setup VMs that they do not need and ask questions

Because the OP is having trouble figuring out what the problem is. If it was as straight-forward as "These guys don't do any work" then the solution is pretty obvious, isn't it? He also says, "Two of them just work with minimal supervision". Well, if everyone was like that, we probably wouldn't need managers.