Yeah, I know what you're talking about. Currently, once you have pretty defined what your info bubble looks like, it's hard to really break out of it :)
I'll state from the beginning that as a user, what I want in terms of discoverability is to see things that are popular (or seeing intermittent popularity) to other people, but that do not fit within my self-built echo chamber.
The way it is right now, if a post is good it will not stay in the unshared section for more than a few minutes. However, if it's not shared by someone with the followers to get it out there and exposed, it'll languish without any real exposure.
At least, that's the impression I get.