its not really an echo chamber, lemmy unlike reddit is decentralised, so nothing is stopping a dbzero user from just making an account on feddit.org and interacting with them, in reddit if the admins decide to ban a community that community is just gone.

also having an echochambers isnt bad, like an instance like blahaj should be allowed to exist and not federate with instances that have a lax policy on transphobia, and thanks to lemmy’s decentralised nature you can join or make an instance that does have wide federation