Riot does seem to require playing LoL[1]. Not sure how is Facebook relevant here.

[1]A random job posting from Riot http://www.riotgames.com/careers/10838

"While our engineers come in all shapes and sizes and work with many technologies, we expect every engineer at Riot to be:

Player-focused: you’re a gamer whose passion for games (especially League of Legends)"

Thanks for the citation! Wish I hadn't been downvoted for asking an honest question, but this clears things up.

I have not downvoted you but I imagine many people here do not like non sequitur arguments.

It's not a non sequitur at all. Just pointing out that it's not unreasonable to imagine someone working somewhere without being a user of that company's product.