Maybe 2 or 3. All for the same reason. They are trolls. Their posts are primarily made to incite others rather than add anything of value. I just got tired of wading past their posts to get to rational opinions.
At least some that love high post counts sometimes add valuable insights. My short listers tend to post a wiki article they don't understand or poke others for a reaction. No thanks.
For me it’s 2. It just makes the forums more enjoyable. When every post is an argument or copy and paste from google or wiki. Can’t fade it, so I ignore them.