I don’t know what their target audience could possibly be. If the game is so visually unappealing that the customer doesn’t care about frame rate or resolution, then it’s likely they already have the capability to render that with the console they already have. Stadia needs to convince people they have a better product than what consumers have today. Instead it looks like a step down and you still have to pay full price for the games. People can finance a console purchase over a couple years for a little more money and enjoy their experience more while having a structured monthly payment.
But why won’t people just use the devices they have today to play such a game? I don’t even know how many physical CPU cores Google will give each machine, but imagine running Civ on some server grade processors with tons of cores. That could actually be a good experience but I doubt Google could make money if they were generous in this way.