Disneyland is a very complicated place with endless things to do and different directions to choose, but you walk in through one simple front door after buying one simple ticket, so it's not as scary to make first approach. Once you're in, you can craft your own adventure, but you have to get in to have the chance.
I know it's somewhat in conflict with a federated future, but for the "mass migration" portion at least, there are just a LOT of choices to make before you've experienced a single benefit out felt delighted by the familiar features of these communities. For that reason, many will be too intimidated to even start.
In the short term it will keep us small and keep certain low effort people out (maybe why energy is fairly ideal here, for now at least). In the long term though, may mean we never gain the mass to threaten the reddits of the world.
Maybe a centralized entry point run by someone else (or the Lemmy devs themselves)? It could explain concepts unique the fediverse and why picking the instance you make your account on is important. From then on, people don’t really need to worry about what instance they’re on (unless the instance they’re on goes on a defederating spree), which removes some of the complexity