It's much more about avoiding potential legal liability issues in the future. I wouldn't be surprised if all the large tech companies have similar clauses.
The reason every company in the world has this document somewhere is that crackpots will send random documents to them ("here is my proposal for an Apple telephone, I call it the Apple Telephonogram Pro, and it uses lasers") and then later sue them when they release an overlapping product ("the iPhone is a rip-off of my Apple Telephonagram Pro!").