You want to buy a pizza for yourself or someone else. At some point your transactions will have been gathered together to do so, either in the merchant's wallet or elsewhere.
Hey presto, there's some information. Either about liking to buy pizza, having friends in country X, or being based in country X.
Trace it backwards, you have a list of people potentially involved.
I'm not saying that a single transaction will identify you. However, much like that EFF browser identity page, it doesn't take many bits of information - plus a few "likely good with computers" type guesses - to start putting together a list of very plausible identities.
Hey presto, there's some information. Either about liking to buy pizza, having friends in country X, or being based in country X.
Trace it backwards, you have a list of people potentially involved.
I'm not saying that a single transaction will identify you. However, much like that EFF browser identity page, it doesn't take many bits of information - plus a few "likely good with computers" type guesses - to start putting together a list of very plausible identities.
You're kidding yourself if you believe otherwise.