It could be a really good use case for a crypto currency. But eg. Bitcoin needs too long for a finished transaction (I don't want to wait ~10 minuntes until I can read an article). And you still can track down a person who purchased (separately) two articles by his keys or analysing the block chain.

I know we've a lot of crypto currencies right now, but I really hope that there is finally a new one coming, which is just simply fast, secure and somehow helps you paying anonymously.