The phrase "Black lives matter" carries an implicit "too" at the end; it's saying that black lives should also matter. Saying "all lives matter" is dismissing the very problems that the phrase is trying to draw attention to.
If you expect everyone to acknowledge the existence of the 'implicit too', then it's only fair for people like me to expect people like you to acknowledge that all lives implicitly include black lives as well AND saying 'All Lives Matter' does not in any way imply that one is ignoring your right to exist.
Also, I would like to mention - It wouldn't mark the end of the world if people would start speaking / writing / typing complete words and forming complete sentences. It really would be a lot more helpful than an unnecessary (and ill-conceived) rant (irrespective of the support it gets from the mainstream media or social networks).