Firstly, it speaks of how ignorant we all are, as a public mass, of how the world actually works, even the reality of an "obvious" situation we aspire to be commenting about. Because you cannot actually "delete facebook". Neither can you "delete" the entire service as if it is some "app" on your phone, or old-skool word document on your laptop, nor can you delete the data it knows about you. Even if FB actually deleted the data they had about you, you can't make their AI's "unlearn" everything they got from you, and you can't make their 3rd-parties delete your data as well ( no matter what you well-intentioned t&cs-ninnies might say to counter this, I just don't believe you that there's anyway to make these things happen ). So you can't Delete Facebook. The first rule of Facebook is: Facebook is eternal.
Secondly, even if you go ahead and delete your account, your protest is impotent. Your victory is symbolic. Your effort at self determination will be undone. Because it's sort of like people saying they were going to leave California ( or the US ) if Trump got elected. So you can do it, but it won't change anything. It will probably end up severely disrupting / hurting your life. And in the end, you most likely won't do it. What this reveals about our ignorance is how powerless we actually are, and how ignorant we are of what Facebook has become. It has become a utility. It is ( mostly ) essential. Even if you do not use it, other services assume you do, and your access to those is gatekept by your ( non-existant ) FB account. And if you do use it, or use Messenger, or Whatsapp, then it is a good way to stay in touch with people you know. And if you really use it then of course you know why you need it. Second rule of Facebook is: Facebook is necessary.
So the third thing I like about this is, how ignorant this hash tag reveals us to be with regard to the way to deal with Facebook. It's not about individual actions. It's about the collective. FB has begun to impinge upon the collective. It has become a utility. And it exists forever, despite the actions of individuals. When it goes rabid / stray, what is needed is collective actions to bring it back under control of the commons. Within the bounds of the common good. Only regulation can subdue Facebook to the useful and the good. Not protest. The third rule of Facebook is: It's a utility, stupid. Regulate it.