Because people would be posting tons of stuff like that. That thing is LARGE... If you posted that, it would shove the forum display page/layout WAY out to the side and cause everyone to side scroll every forum you posted in. Furthermore, many would enter POOR HTML code, wrecking pages, causing problems, etc... It's just not a good idea to let every joe smoe code HTML on your pages.
------------------
Dan McClain, Editor
The Mustang Works Magazine
1991 Mustang GT - NOVI Supercharged 377 Stroker
1999 Ford Lightning SVT - Supercharged 5.4L Triton