It's a genius financial and strategical move, predicated by having a lucky monster success elsewhere in the company that required a quick influx of resources (Fortnite). They can effectively write off a failed game over the next 5 years, and reduce their tax burden as a result. They then act as a "benevolent" actor to the gaming development community by giving away assets that have no financial incentive to them. So they get a nice influx of resources and get to advertise to a new pool in the same breadth. That's a win-win.
EDIT: I should also note - I was a benefactor of shifting my payment from Paragon to Fortnite. Given that it had no variable cost to give me $20 worth of skins in Fortnite, that's a pretty solid user acquisition strategy.