There is a problem here with high karma correlating with being in the same echo chamber as everyone else.

I think it depends.

My observation has been that people on HN value facts and first-hand knowledge, and reward such.

Because of that, I believe that someone who has been on HN for a long time with a lot of karma must know something, or have lots of experience.

Someone who has been on HN for a long time and has low karma makes me think that they don't have much knowledge to contribute and I view them more skeptically.