There's lots of small reasons why. You can't tell your employees about that new phone feature you're developing if it lands on Bloomberg a year ahead of release

There's lots of small reasons why. You can't tell your employees about that new phone feature you're developing if it lands on Bloomberg a year ahead of release, because then your competitors might one-up you. You might not be able to openly divulge ongoing security risks because external actors will definitely exploit them once they land on Bloomberg. You might not even tell them the intricate details of search-engine improvements or Youtube spam detection changes, because if it lands on Bloomberg the external SEO market goes crazy and destroy all your hard work... I could go on, but there are a lot of things that would arguably make a lot of sense for you to divulge to your employees, but that you just cannot if you can't rely on them sticking to their NDAs.