Those of us who respond here regularly are reasonably confident that we know something about the language we teach, write in and/or are interested in. However, none of us believe that we know everything. One of the pleasures for me of working in this forum is that I frequently learn new things.
No matter how much we (think we) know, we are all human, and we can make mistakes. When we do, we need to rectify them as soon as possible. We old hands cannot help people if we lead them to believe that we are always right and that, in case of misunderstanding, they must necessarily be wrong.