Saves having to rip up your new hardwood floors.
So, we had hard wood floors installed almost two years ago. They extend into the half-bath in the master bedroom. Long story short, the wax ring didn't quite seal all the way (evidentially, about 1" didn't seal along the front). Now we have several wooden boards that have begun to rot out, and I even had shelf-like fungus under the porcelain base.
I'll be sure to make sure we have plenty of wax next time.