There are personal opinions in these web pages. This is correct.
Is it restricted to some pages?
No, all pages contain opinions.
Hopefully every statement is compatible with its author's opinion.
This is a condition for him/her to be responsible.
What is not the general case is that this opinion would be an official opinion --whatever this would mean. I.e. being official is a state in which certain pieces of information may be. Some pieces of information never need to be official, but it would be hard and useless to predict which ones will and will not.
The life cycle of information never ends. The information may be reused, adapted, refined, corrected. Most of the time, it is mostly opinion. From an SCM point of view, it is important to ensure the continuity of its representation: that it is maintained in-place, so that the relationships it enters in with its context are stable; so that the changes are minimal and localized, and their effect is controlled.
Making an information official affects only a version of it, and is only temporary.