“Defamation is defamation no matter whether it is written on paper or on a blog,” it said in the article.
It’s usually a bad idea to give legal advice if you’re not a lawyer, on a blog or not. Other certain speech is probably also a bad idea (e.g. investment advice, tax advice, etc.) in such a forum.
If you think about it before you write, you can probably balance your need to express an opinion with some basic life risk management.