I think the federated nature of Lemmy will be beneficial in maintaining the integrity of communities. Unlike reddit, where everyone jumps in the same massive pool together, on Lemmy you have to pass through the filter of having a home instance. Hopefully the home instances/servers can help keep in check the behavior of their own users. After all, if any instance is a haven for toxicity/spam/bad behavior, other instances always have the option to defederate from them. So I think there is a natural incentive for instances to police their own user base, which hopefully translates to better behavior in larger communities as well.