I expect this will be a controversial take but hear me out. I think it's futile, to an extent, to fight against so-called echo chambers since it's so ingrained in human tribal nature that the alternative ends up being worse for us. Having some key points of consensus is not necessarily all bad, it mirrors how socialising works in the real world, where people tend to connect with like-minded people, groups of people may not agree on everything but usually have some core values in common that tie them together (note, I still think that Lemmy has less of these types of values in common than most real world friendship groups, but it's closer to it).

On the other hand, throwing everyone together on the same corporate social media platform is something recent and unnatural. People don't have respectful debates and listen to each other there, they argue, get angry, and dig deeper into their beliefs. For example I would never have made a comment on Reddit, like this one, that I think might be slightly against the grain of the thread since you just get shouted down by defensive people who have already made up their minds. Here on Lemmy I don't expect everyone to agree with me all the time but I believe they might at least listen, so I feel freer to express myself, then again I do have some core values in common with most people here which is what enables that.