If this were completely uncharted territory, you might have a leg to stand on here. But you are correct that this is exactly how Facebook started, and we know exactly how that goes, the poster is correct that this just leads to harassment at scale.
The author's response was the main problem, showing a complete lack of character or ethical concern. There is a world of difference between being a hacker with a sense of rebelliousness and a jerk who thinks there should be zero consequences to their actions.
"There is a world of difference between being a hacker with a sense of rebelliousness and a jerk who thinks there should be zero consequences to their actions."
Given the external consequences of certain actions, for all intents and purposes that "world of difference" may exist only inside their skull.
If we're using the Facebook example to call this unacceptable, we should really be fighting a lot harder against Facebook itself. Because it still has a reasonably positive reputation overall and it's affecting billions of people.