1) The problem is not "new user" the problem is "new users." It's not a feature I'd use all the time, either - but it's a feature I'd like to have for, say, yesterday. 2) Hubski heavily emphasizes personalization - I think (but obviously cannot prove) that it's far more likely to have a user with an account that doesn't comment than a non-user who suddenly signs up. I can back that up with a little data; I see lotsa lotsa users that pop up and follow me, but when there's a Reddit wave, they usually start commenting pretty much immediately. 3) If they're doing anything other than sending a PM, their comments will be visible in threads... the person they're responding to (assuming they're ignored) simply won't get a notification. That's the thing about "ignore" - it's much less of a behavior shaper than people think.
Perhaps to assuage fears, there should be both an "ignore" feature AND a "snub" feature. Ignore will remain the same, but "snub" will result in a message like, You know, just to make "ignore" seem less threatening.humanodon evades your handshake and refuses to make eye contact. He also kisses your wife on the cheek . . . a little too enthusiastically.
It took a long time for me to become an active user on Hubski, I would revisit it every once in a while when I was "out of Internet" but frankly, it took me a while to get the whole community/commenting aspect of it. You all acted like you knew each other! What was up with that! It's not that it felt insular but it definitely felt like a community and I wasn't used to that online. I would spend time thinking of questions and deciding whether they were good enough to be #askhubskis or not. I think my first askhubski was when I began to feel more involved. I had some sort of thorny situation and I thought, "This would be perfect to ask hubski! I bet they would have some really great input." That was probably when I began realizing it was important to pay attention to usernames. I never paid attention to them on Reddit - a key difference in how to approach sites, i think.
We've been here the same amount of time and only now do I feel I'm starting to become an active user on this site, precisely for the reasons you stated. Because of that community aspect where everyone knows who each other is, I felt significantly more self-conscious about what and if I should post.