It seems that Zuckerberg is not the only person who can not be blocked on Facebook. There are several of them. According to an email sent by a Facebook spokesman told the blog Mashable, this is actually a protection. It only comes into play when a person is blocked a number of times, as in viral campaigns instructing members of Facebook to block someone. From there, the system is activated to “protect [on Facebook] experience of people attacked” by such campaigns. Overkill? Perhaps.