I think there's some real sketchy puzzle design in Grim, but the broad assertion that all the good parts of the game are non-interactive is major hyperbole and part of a narrative (one that, as you point out, finds a lot of sympathy in the comments) that makes Jimmy's take more familiar than dissenting. That Grim would have benefited from superior puzzles is a far cry from "Why is it a game at all?" but the former is more the position I take on it.