The “make a fork” thing is part of the issue, I think. In general there’s this culture in the open source community that if you want a feature, you should implement it yourself and not expect the maintainers to implement it for you. And that’s good advice to some extent, it’s great to encourage more people to volunteer and it’s great to discourage entitlement.
But on the other hand, this is toxic because not everyone can contribute. Telling non-technical users to “make it yourself” is essentially telling them to fuck off. To use the house metaphor, people don’t usually need to design and renovate their houses on their own, because that’s not their skillset, and it’s unreasonable to expect that anyone who wants a house should become an architect.
Even among technical users, there are reasons they can’t contribute. Not everyone has time to contribute to FOSS, and that’s especially notable for non-programmers who would have to get comfortable with writing code and contributing in the first place.
But how will you get a “universal” view of the fediverse? No single authoritative view exists.
You yourself acknowledge that this is complicated, but I honestly don’t understand what appeal a hacked together fake centralized system would have for people if they don’t care about decentralization in the first place. Any such solution is almost inevitably gonna end up being janky and hacked together just to present a façade of worse Reddit.
Lemmy’s strength is its decentralization and federation. It’s not a problem to be solved, it’s a feature that’s attractive in its own right. It doesn’t need mass appeal, it’s a niche project and probably always will be. I don’t think papering over the fundamental design of the software will make it meaningfully more attractive to the non-technically minded.