It's amazing how many people have started to use Twitter as their primary source of communication with the companies they do business with. Twitter enforces complaints to be succinct and to the point and since it's asynchronous, you can get on with your day, rather than being on hold with elevator music playing.
And like the author states, it's such an easy win for the company, even if the reply back is "Give me a call at XXX-XXX-XXXX and I'll help out" or "Send me an email at XXX@example.com".