Like I said, I font agree with the conclusion that games cannot be art. But I agree that the quality of games is shit shot when compared to film or literature. This goes beyond the "90% of everything is crap", even the best games have offered so far is still pretty bland art. The main advantage games has as art is interactivity, and I would maintain that it's a pretty huge advantage, but visually and narratively even games that try to be more than just games are lacking.
I think that is the crux of the issue, as well. Most games do not try to be art, they try to be games. Ebert at the end makes the argument that other games, such as chess or mahjong, are not art either. This echoes his previous sentiment of "art cannot be won". I don't agree that art necessarily must be "unwinnable" as a definite like he put it, but I do recognise that there is a big difference in what games aim to do. Just like chess doesn't concern itself with anything but the game of chess, the computer games I am currently playing, XCOM 2 and Crusader Kings 2, don't concern themselves with anything with anything but their own gameplay. These are great entertainment to me, but they aren't trying to be art entertainment. They're just games to play.
I want to compare this to, say, family photos or videos. Film can be art and photography, but that doesn't make everything that's filmed or photographed art. The purpose of family videos and photos isn't to make art, but to capture, and perhaps to share, memories. You could claim that they're art simply by being in the medium of film or photograph, but I would disagree. They don't have any purpose beyond what they are.
Of course, there's been a big upswing with games that want to be more, that try to be art. But at the core of it it's still rooted in the gameness. That's why we still call them games, why we still claim "games can be art!", why there is still so much derision against "games without any gameity"/"walking simulators". I think games as an art form will become more accepted as time goes on and the media becomes more prolific, but looking at the sortiment available today and in the past, I really can't blame anyone for thinking games aren't art.