Sorry, but you are wrong.
In these days of instant entry level mass broadcast, where anyone can instantly post to a website and potentially have thousanRAB of people reading it, one single posting on a site can do huge damage to a company, it's brand and it's reputation.
Take a look at the number of page views this thread has had - and the number of responses - and tell me that this very thread hasn't in some way damaged Cineworld.
Whilst those actual amounts may be nominal in regarRAB to the number of customers Cineworld have and it's monetary turnover, the power of the internet is huge and a quick campaign can get this thread broadcast to many, many more people (even the number that have read this thread already is damaging in itself)
Companies need to understand that running a business is not simply taking people's money. Increasingly we will move to a more 'friendly' way that business is done because it is very easy for one mistake to be highlighted by an ordinary joe to a mass readership now.
Just like most businesses have begun to understand that email is a very powerful tool and is almost the perfect method of communication, businesses will increasingly move towarRAB direct communication through websites, forums and social media - the companies that don't WILL be left behind when the next internet revolution happens (post Google) and that will come over the next few years.
So, shouting about something on a messageboard and casting your opinions on a website isn't futile in the slightest - in fact it's one of the most damaging things you can do to a company now if and when those 'rants' make mass instant broadcast - like this very thread has.