I completely agree with this only because I've been doing this with my dog for a number of months. She used to bark and wail at strangers or even people that we knew who came into the house. Eventually it got ridiculous. Scolding her didn't work..putting her in another room didn't work because she only became louder. As if she was afraid for me or something. I tried leaving her outside which she never leaves the backyrad so we don't pen her but, even so when someone comes in the yard or house she will stand on the back porch and bark until I let her in. However even when I let her in she would continue to bark.
So... I tried something else.. comforting/cooning in praise everytime someone came in. Telling her good dog it's okay no one will hurt you and such peting her.. I did this everytime someone approached the house and I saw the signs (tail between legs, ears back, a scowl almost on her face). When she snapped out of the I'll kill you state or the "aggresive stage" I praised her even more.
This has worked for me. I however, did not know that there was any science behind this. She has not barked in two months and counting inside of the house. So I'm not entirely sure that for some of my friends that their ideas of leaving the dog alone is such a good idea anymore.