I used to double-click on user names to view the profiles, but it seems like that was removed recently. I wanted to provide some feedback that the feature was useful, and the UI is a bit more confusing now, because double-clicking now just opens and closes the profile, and some users might not figure out that they have to click on the 2nd avatar to view the profile.
With double-clicking, users who click on the username or smaller avatar multiple times out of frustration will still end up on the profile page. (That’s how I discovered it.)