I'm not sure I can effectively put it into words, but I have the impression that both statements ("Things only 'work' and 'don't work' in relation to a specific individual or a group" and "game design is a skill that can be learned or developed") can be true at the same time. There are many aesthetics, goals, and styles of games and play, and many different player expectations. I think the first statement basically means that games are not objectively good or bad, which I agree with. The second statement I also agree with: you can get better at expressing certain aesthetics and designing for certain principles or player expectations.
Although I have never actually played Pathfinder, I have the impression that I wouldn't like it and that I would have specific gripes about its design, but that doesn't necessarily make it a bad game. It maybe makes it a bad game for me and for the outcomes I expect from such a game. So one could argue about whether or not its design is good for the style of play it wants to produce/encourage, and that could teach us some things about design. But because people want different things from a game, ultimately games will always "work" or "not work" only for specific people.