Lemmy is a perfect replacement for Reddit because it’s not Reddit. The feed was curated and not as organic as the voting system made it seem. As time passed, it became more of an algorithmic engine for dopamine extraction. Sure, I had some great times there, but times change.
Lemmy is not a perfect copy, but it is a healthier replacement in some ways. Separate instances do amplify echo chambers, but, they mildly serve to keep different groups separated. Some personality types are just not compatible and that is OK. We still have common spaces and can still be civil, mostly.
For now, there isn’t as much room here for business. Sure, we have plenty of porn but this platform isn’t as easy to exploit for money as Reddit was. No centralized advertising structure is awesome, IMHO. (Some clients still leverage ads, but I don’t use them.)
Its probably more accurate for me to say that I think there is a gradient of people between instances. Using politics as an example, and without details, people seem to gravitate to instances where they are with like-minded folk. Combine that with local or global filter preferences, and echo chambers start to form on a per-instance basis. Communities of higher interest will likely be on the users home instance, after all.
But yeah, I am fairly sure most of us browse /all and see content from all over Lemmy. We still mix and mingle, but are still lightly bound by our own filter preferences. See above paragraph.)
(I am not trying to dictate hard rules of behavior, btw. Lemmy is too diverse for anything definitive.)
Personally, I try to only block specific communities and not entire instances. That has seemed to keep my personal feeds fairly open.