AFAIK, the ones related to my interests are. But I get your point, and like this discussion, my interaction is spreading into new areas for me, and I think I need to see what I may have been missing.
So I have started adding a few people to my follow list
Same here. I pick and choose who I follow (many are on this thread). I do not follow the busier Communities like AR System because that would just flood my Inbox and at that point I don't see much difference than just going to the Community directly and reading through the threads (maybe I am doing it "wrong" and this is why I am not very active in AR System ). Form the busy Community if there is a topic that I find interesting I'll follow it.
Like LJ, if Doug posts I want to read it and following people have brought discussions to my attention that I would have otherwise missed. I have one or two friends that are very active and do not follow them in my Inbox because I wouldn't be able to keep up. Honestly the people I have in mind are very helpful and are commenting on some threads that I do not have much interest in (like what is the difference between and Active Link and Filter). These active friends already helped the person and beat me to a reply so why put it in the Inbox.