Are hardshell cases bad for the Macbook Pro?

I've been reading around on some forum sites for the best case to get for a macbook, and I've ran across a couple of posts saying that the extra weight added on with a hardshell case ends up messing up the display over a long period of time.

I can't find the exact post otherwise I would link to it, but it was from a former "apple genius" and I can't stop thinking about how he might be right!

Does anyone else know anything about this?