Ok I understand user private messages but this looks a bit different. How did you know I asked this? I didn't ask you. And why can I post without having another user to talk with?
I won't speak to how @DrClaude found this profile post discussion, but I can tell you how I found it: Before I replied to your post about investigating wave function collapse I took a look at your profile (looking for a hint as to which books you might find most helpful) and saw it.
And that's the key to using profile posts: you're leaving a message for anyone who comes along later and views your profile.