Tired of the racism biracial people experience !!

Lately on social media (mostly on Tumblr) I have become so frustrated with how people (full-black women especially) treat biracial people. It is very discouraging as a mixed person to see black women talking down to us, saying we shouldn’t be considered black, that mixed people have more privilege than dark skinned people and that we think we are better than them and we have “light skin privilege.” I understand black women do receive a lot of slander and racism but why do we feel the need to put others down? I have never once thought of myself as better than a full-black person just because I’m biracial/mixed. It’s just really sad to see because you think you can fit in with one side of your race and they just act like you don’t belong? I would really like some opinions on this from anyone who has experienced this themselves. !! I’m not trying to offend anyone but I have been noticing this a lot lately!