Thread:Nbajammer/@comment-1352718-20150908215904/@comment-691135-20150908232736

The reason they aren't allowed is that they are unofficial. The Facebook account is an account, not a page, and thus cannot be verified for authenticity. It might be him, it might not - and there's no way to prove it. So we cannot accept it. Tumblr, like Facebook and Twitter, is generally disallowed because it is editable by anyone and can be made to say whatever - there have been repeated citations of a certain Tumblr account that I disagree with largely because, again, it cannot be verified to be official and the rule states you cite the object being posted not the account itself. The sources page of our Style Guide outlines this pretty clearly as to what is or is not acceptable as a source, and why.