It looks like, over a span of four days, they had 600 engineers (heavily biased towards UK engineers) answer survey questions. The vast majority of the higher failure rates were for the whether "Development starts before clear requirements, no complete specification, significant changes late in development."... which is placed under "Agile Requirements". Of course, these are things that agile recognizes as factors that create risk, and the methodology is about trying to mitigate said risk as best as possible. So, it's not an indicator of methodology but of the context. Yes, if such risk never presents itself, you are much less likely to fail, regardless of methodology.
https://www.engprax.com/post/268-higher-failure-rates-for-ag...