I think this highlights a very good point. It's totally ok for everything to gravitate to a central instance as long as that instance is run in a way that everyone is happy with. The key is the the moment something changes and users aren't happy, the decentralised nature of Lemmy gives those users an exit strategy - a way to replace the bad instance and carry on.

If a single Lemmy instance becomes the new Reddit and then pulls a move that angers the community the way Reddit has recently, users wouldn't be reduced to protests and hoping that management listen, they could just spin up new instances, mirror the content, and carry on like nothing happened.