It doesn't matter what your intention was, the point was that that was what it did. You didn't think hard enough about how people would use it given the (lack of) constraints and moderation you designed it with and you didn't take responsibility / accountability for what you had facilitated.

Your response to this seems to be: "People need to be more thick-skinned, I would take it down if they asked & it's unfair that they escalated to the dean." as if that somehow invalidates the criticism you're receiving. It doesn't. The fact that you don't really own up to that shows a lack of emotional maturity which makes it hard for people to feel sympathy for you. Until you actually understand why people had problems with what you made, you won't get a lot of sympathy for how you were treated either.

It's like those videos where some clueless racist spouting off garbage on the subway eventually gets punched by someone else. Yes, the assault is definitely "more" wrong. But you won't find a lot of people feeling sorry for the racist.