There are plenty of good HTML editors online or to download.
Well, why would anyone want to learn to read and write a foreign language, when there is Babel Fish or Google translate available?
Also, an HTML editor would just be overkill for most posters on FR. I only use 4 types of tags regularly when posting here: paragraphs, images, hyperlinks, and text formatting. It would take me longer to go to an editor to parse those out for me than it takes me to just type them out.