First I was thinking that they wanted to get Fortnite into everyone's list of games, but seeing the above, it means they need to at least make people download it, so there is a chance they will start playing it.
I wonder if players are starting to abandoning it and they are trying to find new players for it, to keep the hype around the game strong. If there is a case of players abandoning Fortnite and that becomes news on sites, that could lead to an acceleration of players abandoning it and moving to other, newer games.