He (or me) could only do that If we had been logging our traffic. Now its too late, I cant match that with an IP anymore. That doesnt mean you are anonymos. Give me a time in UTC before you do a purchase, with 24 hr advance warning so I can start logging, and lets see if its as anonymous as you think.
Yes. And give me the address and time of a street based drug sale in advance and that is no longer anonymous as well.
If you use bitcoin properly, it can be quite anonymous.