he thinks 16:10 is what everything should be optimized for.
If that's the case I think he misunderstands what the site is about, which is basically "wider is better." 16:9 is wider than 16:10.
Also more to the point 16:10 is not a mainstream ratio and is slowly being killed off anyway. You can't even find a 16:10 monitor in a retail store anymore and eventually they will stop making them. It would be unwise for developers to focus on a PC-only aspect ratio which isn't even favored for PCs anymore.