Tumblr is crap because it is full of self-righteous bitches who have no real idea how the world works and yet insist on dictating your thoughts.
crap reason    good reason    not sure
People also think Tumblr is crap because it:
's because no-one tumbles ... down a hill [crap good]
requires me to screen cap ICBI to reblog. FUCKING SCREEN CAP. WHAT DO YOU THINK THIS IS? THE 00'S!? [crap good]
still has enough good to bad content to waste all of my time [crap good]