"As far as I know, this is a forum in which both positive and negative opinions can be expressed as long as they are expressed respectfully."
That is correct. Everyone should feel free to comment as they wish.
That said, please do not engage other posters personally on their "refusal to acknowledge", "talent for hyperbole", etc. While you are not using bad language, you are still making a negative statement about the validity of another poster's point of view. And that is looked down upon in the WW board.
Or better put, it is not allowed.
If you feel you have come to an endless loop with a particular poster on a particular discussion, just acknowledge it and move on.
Thank you and enjoy the board.