Scalability. Most federated Lemmy instances are hobbiest run projects started by every day joes and privacy advocating sysadmins. These instances can handle a modest amount of activity. Lemmy.world is slowing to a crawl and barely working due to being overloaded. At the scale of tens of thousands of active users you NEED proper infrastructure and a dedicated team. These are not things that come easy when the instance generates no revenue besides meager donations. Lemmy.world is looking for on call system operators willing to contribute 5-10 hours per week. Good help is rarely cheap let alone free.