Plagiarism is fraud so I'm all for downvoting it... but "shitposting" and "spam" is subjective valuations with no objective measure.

Sure it is subjective, and I'm subjectively using my stake as I see fit. If someone else thinks it isn't spam they can upvote it. If I was a jerk, I'd flag you for being a rude idiot, but I don't.

What I downvote is plagiarism, spam, or some type of abuse, I could downvote far more outside of that scope but I choose not to.