EA has this with Origin Access (2 tiers, $5m/$30y and $15m/$100y), alongside Ubisoft with UPlay+ ($15m). And I guess platforms like Stadia would fall under this category.
Of course, the games are specific to the publisher or the partnerships the platform has.
I guess it's not a fair comparison though, since you can't really subscribe to steam. So I regret saying anything.
Has anyone tried that model? "Pay us $30/mo and play whatever you want."