The discussion is so bad because the article is.

There’s so many nuances around assets, trademarks, copyright, monetisation, cheatware(?), multi-player etc but the article ignores all of it and goes for the straight freedom angle. How do you even have in-game purchases when you can’t control client code? Do we even have a single example of FOSS and mainstream game that made money and was multiplayer?

Terrible slop and I am flagging it.