Two points. First, when you're requesting a patent be reexamined, you're talking to a patent examiner. To a patent examiner, patents are the most convincing form of prior art--if only because she's used to reading them.

Second, it's widely thought to be risky to have your engineers read other people's patents, because then, if they later infringe those patents, the court is more likely to hold that it was willful infringement, and triple the damages. So, if you've got to have your engineers spend time reading patents, looking for prior art on your competitor's patent, you generally want them to be reading your own patents.