I mean, you dont have to do it personally. Just someone from your server has to tell the local server "hey, im interested. Please give this server a feed" and then everyone on that server now gets a feed. You can also use the community search and just select all and then it will search out and then you can subscribe from that page. It's basically a master list of communities. For instance https://lemmy.world/search/q/pokemon/type/Communities/sort/TopAll/listing_type/All/community_id/0/creator_id/0/page/1 then everyone on lemmy.world now has to deal with an influx of pokemons...

I might be misunderstanding but it basically works the way you want it to work but in a different way than you want it to work.