Didn't know about Alyx, it doesnt sound like a game you could monetize in any way. Given its a single player game with few thousands players who have fancy googles :)
The launch and handling of Artifact is a clear sign of valve's hubris or complete out of touch state. Or more realistically pure greed of people who would benefit of it. By people I dont mean valve as company, they make more money of steam in a day that they could have ever make of artifact in a year.
Launch a paid card game at high of Hearthstone, that requires you to buy cards with competitive decks going over >$100 and micro-transactions to play it. Everyone knew it was crazy. And game died pretty much at the launch.
Why the fuck would you even attempt making it a paid game?? Valve has money to keep a game like that free, develop community and get it to stable state before attempting at monetization of some kind.