Probably because- 1. It was not described in Science or Nature.
2. It was described so very poorly, with virtually no useful described morphology or line drawings.
But the pictures are so beautiful, they make me want to drool for hours. ;)
Even though it seems to be a dromaeosaur, this is only based on
the elongate distal caudal prezygopophyses and chevrons. The fused sternal plates are an avian character that could put
it at the base of the Avialae. If this were
true, it would not be good evidence of secondary flightlessness.
Nick