I don't believe it.

And neither should you.

From http://workwithstuartchalmers.com/wp/blog/2012/10/02/banners-broker-it-care/

Well, opinions are like assholes, honey. Everybody's got one and everybody thinks everybody else's stinks. The internet is full of opinions. Why should anyone believe anything they read on the internet?

If a writer has (a) qualification(s) in "A", it means that they know something about "A". It doesn't mean that they know anything about "B", "C"....."Z". However, humans being human, they have biases. Writers write in a biased way. Also, readers read in a biased way. Having (a) qualification(s) means diddly-squat. What does mean something, is backing-up what's written with quality evidence. As I have no formal qualifications in Diet & Nutrition, I try to do that as often as possible. When I don't, it's my opinion.

Many people are intolerant of other people's opinions. No wonder so many "fights" break out on forums, message-boards & blog comments. As a writer's qualifications mean diddly-squat, what's the point in arguing about a writer's qualifications? There isn't one! It's an ad hominem fallacy. Bloggers whose blog contents consist mainly of ad hominems & other fallacies are ass hats.