I always argue that defederation will just result in echo chambers for both sides. And that can ultimately be worse.

In the case of defedding conservative instances, you're also making their instances more of an echo chamber and increasing the likelihood of radicalising themselves further due to them no longer getting challenged on their beliefs, either by conversation/debate, or just by seeing positive posts from the opposite side.

If you have something bad to say about the bbc, defedding is not the answer to get your voice heard and potentially change them. They'll hear about you defedding once (if at all), and then forget and move on. How would people be able to protest if the protest can't even be seen.

(When I say "you" I'm not actually implying you feel these things, I'm just using generalist language to create a point - I agree with you and just extending from your point)