Started reading this article and it starts off ok and then gets all technical and I got bored. Because, regardless of how good that solution is technically, I

Started reading this article and it starts off ok and then gets all technical and I got bored. Because, regardless of how good that solution is technically, I cannot understand what's so difficult about simply making contact discovery optional. At the user's discretion. Like you'd exchange PGP certificates. Why, and how did user control and consent become so hard?