The PDF is a black hole for data.
There’s no way to track if someone’s read it or not, how they interacted with it, or who they shared it with. Ask any content marketer worth their salt how important data and analytics are and they’ll all agree:
If you don’t have any data on what readers are doing with your content, there’s no way to improve on it. You’ll be doomed to make the same mistakes over and over again.