There is a reason. It commits the cardinal sin of fiction: in its pride, it bores me with its pretentious twattle.
The first duty of fiction is to entertain. Everything else is secondary. If you bore the reader, then nothing else matters because no one will read your stuff.
This is the problem with message fiction. Its first objective is to propagandize the reader, to turn him and radicalize him. The ideologue writing message fiction is intending to convince and convert, as a missionary would, and does not comprehend that entertainment does not work that way.
This is what far better propagandists than most message-fic pushers fail to comprehend, especially as those outlets consumed by these frauds shift further and further down the slope towards irrelevance and obsolescence.