I like the writeup and the idea very much. I can think of times when I've used something similar in the past, but the bit about recruiting people to do get milk didn't occur to me at the time.

I'm kinda torn, I see it as a very useful technique to defuse a situation and get people reminded about why they talk to each other in the first place. And of course the actual consequences of having a blazing row, which isn't as apparent when we're separated by keyboards. On the other hand as already pointed out a bunch of other social conventions then come into play. ('Home turf', shyness, social dominance, etc.)

At the very least, it's an important option to have in our toolkit.