OM, you are right. I want to retract my original answer. My first tent in Boy Scout tent was canvas with a wax coating. That one did leak in the creases. Thirty years ago I had a cheap tent and it delaminated starting at the creases.

However, I have a Sierra Designs Jupiter that is about 12 years old and it is showing no signs of the folded map syndrome. Folding is not a problem with modern fabrics.