This is the same as Xbox and PSnow, etc. You have to pay for the service via a game pass or pro membership on top of buying the game and possibly the system before you could stream it.
Even in the case of shadow, you'd have to pay for the service to stream games you'd buy and access off your own/their system.
They stream spotify because they don't want to buy songs and after that current song is no longer popular they move on to another one and forget the first song ever existed. They play video games and when they are done they sell them and buy a new one, never wanting to revisit the old one. They spend $50 on the new game and sell it for $15ish. For that mindset of people this is a great product, along with the digital only xbox one.
I am not implying all kids or youth are like this, mine are and a bunch of their friends are. I prefer gog or a physical copy, but then again i don't buy that many games.