You're technically correct, but I was discussing this in the context of cost-benefit analysis. Yes, you can be "tricky" with Windows, but it's hard, so usually it's strongly preferable to simply move on to another task or find a different way to solve your problem. It's a lot easier to think of clever, subtle manipulations for Linux systems than it is for Windows. Therefore, Linux strongly encourages you to waste your time trying to think of such tricks and then show off how clever you are to all your Usenet friends.
Say that there's a log file where we need to find application errors. It's large; perhaps 70MB. What do Windows users do? Open the file and then hit Ctrl-F to search it. What does a Linux user do? Grep. One is much faster than the other.
You've never used Windows PowerShell, have you?
Besides, if you really want, you can always install Cygwin or some other POSIX shell on your Windows box. I've got it on mine. I occasionally use it for ipconfig stuff, but only because I work for a company that makes packet-routing software and therefore sometimes have to make my network stack do some somewhat unusual things.
Go learn HCI and they will tell you every time that command languages are the most powerful interfaces, but the learning curve is often too steep.
Which HCI book are you talking about, exactly? I happen to do some HCI work professionally, and I can't think of the last time I or anybody else in the industry actually advocated a command-line interface for any product design - even hotkeys are regarded as a sort of obnoxious legacy.
The problems with command-line interfaces go far beyond a simple learning curve. On a fundamental level, the very idea of a command-line interface is an attempt to offload all responsibility away from the system designer and onto the user. Giving a user a command-line interface to your product is little better than giving them the schematics of their CPU and telling them, "Here, with these you'll be able to figure out how to use this machine. Don't come crying to us for help because everything you need is in there. It's not our fault if you're not smart enough to understand it." It's an insult to the user on a very basic level. I don't know what you're reading that makes you believe that HCI professionals consider command-line interfaces "powerful", but if "power" is measured in reducing the amount of thought and effort that the intended user has to exert in order to accomplish a task, command-line interfaces have no credibility.