If we wanted to go all the way, we would also have to delete the metadatas included in the photos of the narketplace's ads posted, not use an address that has been in contact with a CEX for a signature campaign (and I imagine that this is quite often the case).

In absolute terms, you should not buy or sell anything on the forum in order to protect your privacy. You don't know who you are sending your address to.

In my opinion, being careful on the forum is not especially necessary (even if I actively support the principle you defend in this post), because I am sure that a lot of members can be already linked to a deposit/withdrawal made from a CEX via an address they posted here. Even with all the effort, the CEX will cooperate with law enforcement if necessary, and the efforts to protect themselves here will have been for nothing.