Of course that's then like a spider web. If I have email communication with 50 friends, family, and business associates, they all have to use it. Then all 50 of their partners must as well, etc etc etc. Until a short while later, everyone has to be using it. In this lifetime my grandma will not be using bitcoin.
I like a slightly different version. Payment is required, but there is a "legitimate" button that returns the micro payment. If you really want to block an address you can, but you can also simply ignore spam and make money.
The same thing could work for phone calls. You could use it to drop hints too. If my mother calls too much I just don't press the "legit" button and maybe she figures it out.
