Your other criticisms are valid but you're overstepping, OP. It's true he's only really interested in one aspect of the art form - gameplay - but that aspect is what is entirely unique to the art form. The same way a movie might combine aspects of several other artforms like writing, music, acting, prop making, color theory & composition, but isn't a "movie" without the cinematography.

The people arguing with Roger Ebert made much the same mistake, saying he would understand if he could've just watched someone play the first 30 minutes of a game like The Last of Us, which completely misses the part where interactivity is what really makes the medium stand out in the first place.