If I had physical acess to your machine your Windows password would be useless at keeping me out of it. The only purpose it serves is to annoy the user.
What's a hacker going to do, break into my house to see if he can have a crack at checking if my windows account has a password?
This tip is very useful. The comment that you shouldn't do this is not.
Folks who believe we should be bothered to re-enter a password thousands of times over the course of the time we use our home machines in order to prevent a totally unrealistic scenario of how someone would try to break into your computer are missing the big security picture.
It's like saying don't write down your passwords in your wallet. If someone can steal my wallet, or the keys from my pocket, they can get into my house, so why do I care if they get into my computer?