There are lots of things that can't simply be controlled for. Dating for a while before getting engaged and married is a good idea because you really get to know your would-be spouse (gotta make it through the holidays at least once with your potential future in-laws!) but guys who are focused on their partner's appearance and women who focus on their partner's money are more likely to get divorced? Is that a convoluted way of saying "Don't obsess over things about your partner you can't control?"
The quotes in the summary say that couples who elope are 12.5x more likely to get divorced than couples who get married in ceremonies with 200+ people, but they also say that the more you spend on your wedding, the more likely you are to get divorced. How much do they think a 200+ person wedding costs??
Correlation doesn't imply causation, but it also reminds me of a quite from Decisive by Chip and Dan Heath: "Experts are pretty bad at predictions. But they are great at assessing base rates."