Yes, its a problem and a known issue for many of us. You can eliminate the "comments" section, but the tagging area still remains, evidently. And even the comments are a pain to remove, as it requires permissions at all levels to be set to "deny". I would suggest you voice your concerns to Tableau Support, and/or create an Idea in the "Ideas" section of the forum, if you cannot find any similar ideas out there.
Someone posted a very similar question recently: http://community.tableau.com/thread/129743
More info: http://community.tableau.com/thread/124856
So its obviously a problem for multiple users. I am all for more settings in Tableau Server!
Thanks very much for your quick response Matthew! I figured this was the case based on my research but thanks for confirming.