I think it’s always been that way on HN—it could just be arbitrary, not a deliberate choice. I have noticed around here that if you indicate you might use someone’s identity or history as a signal of quality, you’ll get a lot of “argument by authority” backlash. (Except in the cases of someone who built the thing you’re talking about, and tptacek. :) )
On the flip side, on HN I like that the author is kind of greyed out. I never notice it until after I read comments if I look for it, so I generally don't even notice the OP or a comment author.
Other sites like Reddit add little icons and highlights in many places that make the username much more prominent.
