As a rather illustrative case study look at the history of XMPP at Facebook and Google (Talk). Facebook messaging used XMPP until 2015, but it was not federated—but at least you could use client of your own choice. Then they switched to a proprietary API. Google talk used federated XMPP for years, but then dropped server-to-server encryption, effectively cutting off majority of servers, and then dropped Talk in favour of proprietary Hangouts altogether. So the trend is just the opposite—if the player grows big enough and the community becomes self sustained, they will start walling the garden.
As a rather illustrative case study look at the history of XMPP at Facebook and Google (Talk). Facebook messaging used XMPP until 2015, but it was not federated—but at least you could use client of your own choice. Then they switched to a proprietary API. Google talk used federated XMPP for years, but then dropped server-to-server encryption, effectively cutting off majority of servers, and then dropped Talk in favour of proprietary Hangouts altogether. So the trend is just the opposite—if the player grows big enough and the community becomes self sustained, they will start walling the garden.