I don't like the mob thing either but it's how large group dynamics on the internet work (by default). We try to mitigate it where we can but there's not a lot of knowledge about how to do that.
There are a few places in the code that consider karma but IIRC it's never more than 500 (the downvote threshold). It's actually on my list to add more goodies for higher levels - maybe something like linkifying URLs in user profiles - but it would not have anything to do with authority on HN itself. We want the best comments and the best arguments to 'win', not skew things in insiders' favor.
Not sure what you mean about thresholds.