Ubisoft just got a lot more respect from me. I wish more game developers did this.
Not sure if this is made clear but the source code they released only manages rankings, chat rooms and players. There's still the dedicated game server software that is closed. Imo most aspiring game developers would be more interested by the game code than the administrative code that was released.
For one thing, it's amazing how many incompatible chat room systems have been developed by game developers over the years. Some have been smart enough to build on IRC protocols or Jabber protocols and/or servers as a leg up, and I would hope some are looking at options like Matrix today. I've not glanced deep enough if this server is as good an option as those others, but it's still a better option than "roll your own".
Whatever the choice, the fewer game developers that need to reinvent a chat server every (other) game, the more time they can spend on less "administrative" code.
Sure Slack started as "yet another game chat system" before it was decided that the chatroom product was better than the game and a pivot cemented that. But for every Slack there's probably easily a dozen developers that got bogged down in administrative projects, never launched, and never found a way to usefully pivot one of those administrative projects.