If they give more than just a simple "Screw this" type post and actually give some information on why they are leaving then, sure, I could see people interacting with them with intent to help them stay and foster a better community. That takes more than just a one sentence F off to the community here.
Then there are others that drag it out trying to create drama over the situation and don't ever actually state what is wrong - those are who I wrote this article for. Those types just want attention.