I agree with the fundamental premise of the problematic aspects of aggregates, but there is quite a bit in terms of specifics I disagree with.
Bubbles is still relatively new, and I think that’s a large reason for a lot of posts about the platform, it’s not dissimilar to Bear’s discover feed having posts about Bearblog. But that said, I see a wide variety of topics on Bubbles, including the ones you specifically reference in your post. I think it is a little cynical to assume that people (specifically people who use Bubbles) wouldn’t be interested in niche specific things. If anything, Bubbles has widened and diversified the kind of blogs I look at and what I read on a daily basis specifically because there are many blogs that I wouldn’t have added myself to my RSS feed.
In regards to anxiety and competition, I feel as though that is more indicative of the specific blogger than the platform. Metrics exist, you can track your site’s traffic, does it matter? Do the upvotes on Bubbles matter, or the gained visibility? To some people, yes, but if that added dimension is an issue, you can email the guy running it, Ben, and ask for your blog to be removed.
It’s annoying and frustrating (unethical, even) that the process is opt-out and not opt-in, but Ben has gotten back to me the same day each time I talked to him. Bubbles is not Facebook or Reddit, there is not an immutable fixed corporate quality to it.
I completely agree about your points on other directories and tools that should be more utilized, and that people should link to each other more, but I don’t think this is an either/or situation.
I guess what I’m trying to say is that the criticisms are valid, but I think using Bubbles and upvoting what you want to see and positively engaging with it is the answer to mitigate the negative aspects of it. I still think it does more good than harm for the blogosphere.