There is no reason because it's not true. I've used the with statement to help with auto-closing tags (and just readability) in templating and it helps a lot. I've used in on sites which received over 1 million hits a month. It's been used on over a dozen sites and projects from hundreds of lines of codes and even into the tens of thousands of lines of code.

http://news.ycombinator.com/item?id=1605249