Um, it's a public forum. So, there is no "unsolicited advice" nor "unsolicited criticism". It's public. Forums on the internet are specifically designed for this. So, should my neighbor rent a Public Meeting Hall, invite all people inside to "communicate" and then proceeds to talk about how ugly he is, then, yes, he is inviting other people to comment on that "conversation". That is Internet forums, not someone living next door and unceremoniously telling him/her that they are ugly. Apples and Oranges.
OTOH, if your neighbour rented a public meeting hall, invited all people inside to communicate, and ANOTHER neighbour started talking about a third neighbour being ugly, the guy who rented the meeting hall would likely just chuck them out (it's his meeting hall, he's not obligated to allow anyone in or even to be fair about his reasons for inviting or not inviting people).
If not and that continued to be the quality of conversation that was going on, 90% of the people would soon go home or go chat elsewhere, and the hall would soon become full only of those people who thought sitting around discussing how ugly their neighbours are was a fun way to spend some time.