I still think that would effectively imply isolation (at least, moreso than not doing it). What you're describing to me still has a lot of characteristics of an echo chamber. And by spending time on that instance, in those communities, you'll be spending less time on "generic" instances and communities. In doing so, those instances will, in turn, also become less diverse and more echo-ey.
Again, I understand your reasoning (except for the corporate censorship, there is none on Lemmy AFAIK), but I do think it's a step in the wrong direction.