You have already gotten 2 infractions since you have been here and now you are asking another dumb question. However I will let it go and assume you are just not to smart.
The answer to your question is that any OS can be used for web site defacement, arguably all you need is a web browser.
Backtrack is a attack tool so yes there are some tools in the distro which make web site defacement easier. That being said, web site defacement is the stupidest thing ever. I consider people who deface web sites to be like the retards of the hacker world. I have absolutely no respect for them and frankly would have a hard time even calling them hackers.