To me, the golden rule of complaining about poor service is to raise the problem immediately with the service provider and give them an opportunity to address the problem and/or come up with a mutually agreeable solution. However, with the advent of online reviewing on places like TripAdvisor it's become normal to bypass any face-to-face conflict resolution and just trash the person/company in an online review.
There's an ancillary issue associated with online reviewing about the veracity, integrity and impartiality of the anonymouys person doing the review.... They could be a rival simply trying to ruin a competitor for instance. It's very obvious that individuals or businesses on the end of an anonymous and public online complaint would want to defend or explain themselves.
So, in the interest of fairness, openness and balance any platform that carries complaints should accept, tolerate and probably even encourage a right of reply so that the wider audience can make their own judgement based on the accounts provided.
In essence, I think WGs coming on here in response to a specific review/comment about them is a very good thing. If they choose to be beligerant as opposed to conciliatory, well who cares... It just helps shed light on what probably really happened to cause the negative review.