Music isn't why I play videoGAMES.
Sure, it's not why YOU play video games but it doesn't mean that a games soundtrack can't be the main attraction.
Would it help you if there was a distinction between "games" and "interactive experiences"?
Gris is a story told through visuals and music. It uses some quite mild interactivity (ie the game is not difficult) as a mechanism to immerse the viewer/listener/player/whatever in that story.
Again, this is where I think people need to cut indie developers some slack.
This "game" is their vision, their take on the medium, their way of telling their story.
I think that should be applauded.
Sometimes you don't need a ton of content or a challenging difficulty to create and engaging and worthwhile experience.
So while another indie like Hollow Knight may have way more content and way more gameplay they are completely different visions.
It's sad, kind of. The indie scene is really where people can take risks and experiment and do things that would be shot down instantly in the boardrooms of AAA developers. Yet still we have folks saying "music isn't why I play GAMES" and it doesn't have enough content or just outright claiming it's a "scam".
Of course, Indies are not above criticism. I just think it ought to be considered, thoughtful and overall valid criticism.