https://wccftech.com/sweeney-epic-games-store-freebies-help-sales-even-on-other-platforms/

As part of an interview with Gamespot, Epic founder and president Tim Sweeney said that the Epic Games store 'freebies' that have been used primarily to lure gamers to the Epic Games store platform have also been a major boon for the sales of those games, even on other platforms, thanks to the increased visibility.

By doing a bulk deal with a game developer where we basically just pay them for the right to release their game for free for one week on the Epic Games Store, we've been able to get an amazing array of games to gamers and encourage people to play types of games and genres that they never thought about playing before.