Seeing stuff about reddit being posted to 10 different technology boards, plus reddit-themed ones, then reposted further just makes this whole idea a mess. Reposts have to be consolidated into a single comment thread.
Agreed the cross posting is much more visible and irritating. Not sure it will ever be resolved as it is a fundamental architecture design of the Fediverse. I would hate to see another closed source site be the main alternative but Squabbles is growing fast and with the new app looking so good it may accelerate its growth. Time will tell.
I don’t think the architecture has anything to do with it. The algorithms just need improving.
Even if it just shows the post with most activity once, links to other communities versions inside with comments. Uniqueness determined by url and or title similarity.