There are mechansims (see 'soundness') which reward people on the edge between filter bubbles for combining those bubbles. Maintaining a soundness core means resolving disputes between bubbles.

My goal is to gradually expand filter bubbles, rather than try to pop them.

After skimming the "respect" idea, I am convinced that echo chambers are the dominant strategy.

In fact, make a complete subgraph of order 9 or more of people who respect each other. That subgraph has order-N respect that goes to infinity for anyone who has any respect for any of its members, even transitively.