Pretty sure they just read the "it's free to use" part and just left it at that..
OOOORRRRRRR they are douchebag's that don't really care. and still comment using.
sad thing about this, people that comment "STOP SAYING USING" also are annoying. cause
she still gets told "somebody comment on your post" really instead of telling people not to comment
just disable the thing that let's people comment on your posts xD