Fair enough, if that's what you prefer than you might as well, it's more of a personal preference. My main monitor is an ultra-wide, so it ends up using less than 20% of the total width. Though I can see it being tough to have a good solution that works everywhere.
The general recommendation is the keep the measure of the page fairly narrow since studies show that reading text that is very wide is harder than reading a narrower column of text. So looking at the layout from a best practices point of view the author made the right call.
