Opinions are what happens when you either have insufficient information to form a logical position, or what happens when the logical position contradicts your own self-interest.
To me, this suggests that the position that all opinions should be treated with equal weight is the height of idiocy. Perhaps that should be restated - all uninformed opinions should be treated with equal weight, because they are all equally worthless. Once you have facts and logic, you may disagree with others about the relative merits of, say, knocking down your house to build a highway, but at least you're not arguing from a position of ignorance.
That seems to be the main problem with the majority of people today - they're not playing by those rules. As far as they're concerned, facts, evidence and logic do not improve the relative strength of an opinion, so whatever their holy book, horoscope or schizophrenic episode is telling them to do is an opinion of equal weight.
This is the primary reason why debating such people is a complete waste of time - they don't understand the rules, don't care about the rules, and when informed of the rules will disregard them as a matter of opinion.
Of course, that's just my opinion.