[account42]

That ignores the entire set of people who are not contacting you to get something out of you but rather to help you or for any number of social purposes. Those will be priced out much faster than dedicated spammers - most of them by any amount above $0.

[saghm]

I don't necessarily disagree, but that seems like literally the opposite of the objection that I was actually responding to. My point wasn't that this idea is infallible, but that I thought there was a flaw in the logic of the one specific objection that I chose to reply to.