This is not limited to the internet. We learn as children that persuasive writing is weakened by statements such as "I believe", "in my opinion", or "in my limited experience". (I believe that) it is true that such statements weaken writing, and that it should be the reader's job to determine which content is editorial and subconsciously insert the "in my opinion"s where appropriate.

Having said all that, it does seem hard to find intellectual honesty on the internet, but I had more trouble finding a decent newspaper in London so it's not an isolated problem.