For every individual community you would have to pay for a domain, maintain the instance, keep it updated, keeping it secure, and keeping it paid. That’s really difficult already with a single server, let alone multiple for multiple servers and domains. These are also more points where data from other servers can be cached and get hacked/leaked or outright incompatible Lemmy versions.
It’d also still have the problem of multiple communities with the same topic, so it’s not solving anything.
How do you expect people to migrate to Lemmy if these are the ridiculous hoops they’re expected to do to start a community. Instead, they can just go to reddit and click a “create subreddit” button instead. What option do you think they’d choose?