I wonder if it has to do with legal issues in the United States. Just as copyright violations are illegal (and could result in take down notices sent to Steemit, inc by the government), isn't it illegal to include affiliate links without disclosing that fact? It could also just be people complaining about affiliate spam on Steemit and not wanting the rewards pool to fund people's advertising spam.
(and now I probably just broke the law for pasting that image without linking to the source... because I forgot where I first saw it)