Even HN is part of this phenomenon. Sometimes having a highly voted blog article complaining about poor customer experience or corporate malfeasance is the only way to get companies to respond.
I'd guess any public area where people who are the companies customer visits, where you end up complaining in public, ends up being a possible place where this might happen. The only gripe I have with this trend is where people choose to go direct to social media vs the appropriate channels for support. The fear i have is that if enough people do this, normal support channels might get under resourced.
Having said this, i'm often impressed with the support i get when i ask for it. I rarely ask, but i probably should more often. A classic case of "you only get what you ask for", but a good reminder that you should probably be asking more often.