You seem to have misinterpreted joelg236. He made no reference to a growing user base being bad for Hubski per se. That said, I don't think that all types of growth will necessarily help Hubski in the long term, particularly if content is suddenly being posted that is in conflict with the primary objective of the community.
I have a twitter account. In my feed I see what I want to see. I have a hubski account and in my feed I see what I want to see. I ignore tags and I ignore users that don't interest me. My feed looks the same today as it has since I joined, interesting and full of good content. I found this post in the global posts. I don't think growth will be a problem. People that want to "circlejerk" can and will and I won't have to see it. Fine by me.