Epic is trying really hard at making a Roblox-like ecosystem out of Fortnite. They even have a half-stripped-down-but-with-extra-things version of the Unreal Engine (editor) to build games that are a part of this ecosystem.
There’s a significant enough overlap between the Fortnite/Roblox playerbase that Epic thought they could make a decent amount of money by “poaching” the Roblox model and keeping it under their roof.