> They may choose not to do anything with the cookies that remain, but the technical answer to the question is yes.

I think you could say the same thing about IP addresses. A website might log the IP addresses of people who visit them, or they might not, but quite a lot of tracking is feasible. The problem with focusing on feasibility there, is that you end up with an answer like "yes, just like every other website in the world, Facebook can track you when you're logged out." Assuming Zuckerberg has been coached to High Heaven not to gives answers like that, it seems fair to respond to the question as though it was asking about the internal details of what Facebook does with cookies / IP addresses / browser fingerprints.