If the descentralization of social networks continue, we will have to prepare for the eventual rise of the instances wars, where people will start to fight about which instance is better and which one is weird to be in and so on, but that’s for the future of us all.
Regardless of the intention, competition is competition. Two artists whose paintings hang in the same gallery are competing for attention.
Competition happens any time a resource is needed by both and not shared. One who chooses to stop sharing has entered competition. Unless they just don’t want the resources.