It's a constant fight. I grew up in a village. In the 1980s the neighboring city wanted to annex it. The villagers fought against it for about 25 years. Eventually the neighboring city had a vote. All the citizens of that city were able to vote on whether to annex the village. The city ran a campaign saying how good it would be for the people in the village. Obviously the annexing happened because the villagers couldn't fight it.

That's just one example, but it applies to every small, non centralized entity. If a government or a large corporation wants to take it over, it can and will. The one thing digital entities have over other things is space. If someone does take over Lemmy, for example, then the people of Lemmy have the ability to move somewhere else in digital space, unlike the villagers who didn't all possess the ability to leave their land.

Above everything else, the protocols should be compatible with one another.

Long ago, in the US, there used to be a law that said that, if you commit a crime in one US state and then travel to another state, the police in the first state can no longer pursue you and it becomes a problem for the next state to handle. This was one unsung part of why Wild West style bounties were a common thing in the past even on the East Coast.

Now if the protocol in each entity is so aloof from one another that borders become the strength of a saboteur, doesn't that ruin the biggest perk of calling yourself the "united [insert thing here]"? It's also worth bringing up when someone treats the US as one single entity, like when they say "those darn Americans and their guns" and "those Americans are so fat" like one state can enforce a stereotype for the other 49 (something nobody says about, say, Europe).

One aspect I think Lemmy lacks is the ability for some contained discussion. To much leads to feed back loops but not enough discourages niche communities.

This is something Reddit's scale does well. Reddit communities will have most of their posts never make it to the 5th page of All. There will still be break out posts but most likely the only people reading your post are those in your community.

With the current size of most niche lemmy communities you are posting to thise in your community as much as you're posting to who ever is viewing All by new.

Cultural uniformity. There doesn’t need to be full overlap, but in the absence of a government the community needs certain beliefs and behaviors to be universal in order to remain a community.