The fediverse w/the activitypub API sell itself as being decentralised, but it’s actually just neutral. It merely enables decentralised forums to coexist with centralised venues. The Lemmy implementation in particular does nothing to proactively promote decentralisation or counter concentrations of power.
When the software is not designed to steer toward decentralisation, centralisation persists because the network effect is left uncountered. The current stats prove that a mass majority of users and their activity are subject to the concentrated power of a few, which ultimately singularly falls under the power, oversight, and competency of the biggest walled garden in the world: Cloudflare Inc, in the US.
Calling Lemmy “neutral” is overly generous, in fact. When the stock Lemmy web client is queried for communities, it prioritises the giant centralised communities in top rankings of the search results. It’s no better than Google, where Cloudflare also dominates the top slots in web search results. This exacerbates the network effect by cattle-herding people toward increased centralisation.
Lemmy ranks decentralised communities at the bottom. And in some cases the ranking is so low that it’s out of reach when cross-posting. The cross-post mechanism forces a search for the target community, and that search does not support entry of the address of the community that includes the domain. When the list is so long it exceeds the pulldown window length, it’s out of reach.
Yes, we know centralisation is not their deliberate goal. Lemmy developers fear that newcoming novices would unwittingly post in a ghost town without strategically cross-posting and then become immediately discouraged by minimal engagement, and from there bounce back to Twitter or wherever they came from. But it must be realised that the mass nannied steering they have resorted to has cultivated centralisation that defeats the founding purpose of the fedi.
I have my own DB of the data. Indeed I wrote a script that separates the centralised instances from the decentralised ones. So I can already trivially find decentralised venues to post in. But I am just 1 person. Thousands of other people are being cattle-herded into a cathedral. That’s nothing I can solve with software on my client side.
Regarding the cross-posting, indeed it’s a UI defect in both Lemmy’s stock web client and the 3rd-party client alexandrite. Perhaps a coincidence that they both have the same defect. The UI defect is exacerbated by the fact that centralised communities are ranked at the top of the list, which pushes the decentralised options off the list. This steers the crowd into the centralised space.