I've been thinking about exactly this and I think it's because Steemit values honesty, which is heart-melting to this idealist. A lovely young woman, especially when she's not totally boobs-out, but just happy and healthy, is a delight without trying--as so many people are. But someone who thinks we'll upvote tits is sneering at us. Even if they're right, what they're doing isn't participating. Unless, and this is where it does get fuzzy, as you say, they're hers and she's just like that. It's honesty or immaturity at worst in one case, something utterly foul in the other.

BTW, I checked out and upvoted the article you linked. I love it! You're so right that the phenomenon is sad. So sad!