It seems to me that this is very much the same phenomenon as people posting to reddit or ask.metafilter questions or comments that would make much more sense to pose to a particular company's customer service. People think "hey, here's a place I can write stuff", and don't really have a mental model that differentiates between targets. It's a matter of degree, not qualitative difference, between thinking you should ask Reddit why your Verizon bill is being calculated wrong and thinking of "the internet" as a completely amorphous featureless blob that you can type to anywhere and it'll be just as good as anywhere else.