Why do people struggle with STAR method?

I have an interview coming up and the recruiter emphasized the importance of using STAR. I’ve never had to use it in an interview so I was doing some reading and it seems like most people struggle with it.

I guess my question is, why? From my understanding, it’s just a way to coherently structure a story and seems to flow fairly naturally. The problem, the actions you took to solve it, and the results.

So why are so many people talking about bombing the interview due to STAR? What am I missing?