They really really need to do something about the confusing account creation process. Most people ended up on Lemmy.world because they assumed that that was the site you had to use. They were never directed to other instances.
What they need to do is have a lemmy.com website and when you create an account on it it just creates an account on a random semi-popular reliable instance. To spread load. If everyone uses the same platform then the robustness of the platform goes away and we are essentially back to a single point of failure. But now in a more complicated manner.