Hmmm.. I'll have to look it up later. On the test site I setup thedesign.manilasites.com I can select text and hit a B, I or U button to change it, and it inserts the tags for me. And takes them out if I change my mind. I can also change fonts, colorm alignment and insert Ps, lists etc.. So I guess, but turning the text into HTML in the editor, it would help if the writer knew HTML.
So I guess it help by having handy buttons and menus to insert the tags instead of doing it by hand.
For me, when I add a topic to the discussion I get the same edit box as if I login as editor to edit a page. Maybe it only works in IE( I don't know what you are using). I know its kinda broken in Opera on Windows. Check out my test manila site for an example of the new version of the editor[1](it makes you sign up). The stuff on manila.userland.com is old.
[1]http://http://thedesign.manilasites.com/discuss/edit/newTopic