Great question. One answer is that it gives the recipient plausible deniability (I think I'm using that term right, sorta). They have the power to not respond e

Great question. One answer is that it gives the recipient plausible deniability (I think I'm using that term right, sorta). They have the power to not respond even though they probably know who the sender is. And if they don't try to respond then hey they can never be 100% sure of who the sender is. And the sender can never be 100% sure their message was even received. So basically it gives both party's ego/pride some breathing room. As far as the "no hint" case, well yes the service would need to be in the zeitgeist in order to have utility. Who knows maybe one of the big social networks will steal the idea. They can go for it! Just remember little ole me in the credits section somewhere, is all I ask. :)