WOW, lurkette you really opened an issue for many people here.
First, I would note that I rewrote that first sentence about 4 times. I think many of the people who post frequently do try to think through what they are saying.
Second, I doubt that you will see any responses from those who caused you to start this thread. Many don't care because they do see their opinion as the only thing that matters, don't confuse them with facts. Others aren't truly interesting in communicating on a true give and take basis. And still others can't be bothered to read a long first post, they want the Reader's Digest Version.
There are a variety of things that get under my skin as I journey through the forums. I have a particular issue with people who cannot use the correct words to express themselves. It doesn't invalidate their points, but it does jar me out of their train of thought. A particular example is the number of people who don't understand when to use "their" or "there". But, I've just decided to let it go. After all there are plenty of people who post excellent content in their (there?) messages.
I guess my basic message is that it is easier to learn to let go of the little things. Don't lose the bigger picture of the value of the community that we have here.