It isn't ownership, but it does have value, a lot of value for many people.
I've been able to play so many games I otherwise wouldn't have because of it. I can't afford even one $60 game a month, so getting access to hundreds of them for $10 is awesome. I've also been given codes for 3 months of free playpass to give to friends several times, and have played many games with those friends that I otherwise wouldn't have.
And I don't care about owning the games, I played them, had fun, finished them, and don't have a use for them anymore. Why own something you don't need more than "once" (the time it took to finish or get bored of it) when you can spend way less money for something that gives you access to that thing for what is still longer than you would need?

I buy any game I do want to own, but for the vast majority of games, I'm absolutely fine with not owning forever. And with the subscription, you're also free to play any game for however long you want and not have to worry about losing refund rights. I have several games on Steam that I would rather not have spent money on, but it took more than two hours to figure that out, so now I can't get the money back.