Because average reading comprehension is poor. I had to start doing the same thing in work emails so that people would actually read them, because if I didn't they would ignore standard paragraphs that just register as lorem Ipsum text blocks to them.
Once you realise that most people don't read most of the information you give them, it sort of becomes a secret power. You can hide all sorts of things in a five paragraph email, let alone a full report.
I started offering cash prizes in the middle of reports, to be claimed simply by telling me you'd read that bit. Not a single taker. I stopped writing the reports after that, and no one noticed.