Not everybody understands things at the same level. I could read a thread, get confused, and hope somebody can come in and answer in the old thread. Or, I can post my question in a new thread and wait for more experienced, active members to answer.
Me, personally, I don't know enough to offer advice as to smoking and storing cigars. I find others ask questions, and they get good answers. Most of my questions get asked by another poster, so there is no need for me to repeat the question. But I click on every new post and read it.
With that said, I read through the forum rules and saw nothing that said I have to read every new post. If the subject line doesn't interest me, I don't click it. If I start to read a thread, and find it doesn't interest me, I click the back button and look at the next thread.
An Internet forum is really nothing but a bulletin board wthout dialog. Even if it's repetitive, it's still dialog and drives traffic to the site.