Agree with the assertion that academics are the primary consideration. Academics are key and there’s virtually no EC that will compensate if your academics are sub-par.
But… at the same time the holistic admissions process is not simply to take the top test scorers or top GPAs until the class is full. If you are taking the most rigorous courses, for most holistics you don’t get extra brownie points if your GPA is 3.9 vs 3.8. Similarly, an SAT of 1560 doesn’t get you in before someone with “only” a 1550. To some extent, there are groups or tiers of academics that are considered part of a pool of highly qualified.
An example was my son in the last admissions cycle. He was one of 7 applicants from his school to a top 10 college. While his test scores were top 10% from his school, he was definitely the lowest GPA of all 7, probably even by several 10ths of a percent. But… he had taken the most rigorous courses possible and then took even more higher level courses. And his ECs were very good. Of the 7 applicants from his school, he was one of two admitted even with his lower GPA. It wasn’t that the ECs made up for the GPA, it was that the GPA was acceptable even though it wasn’t the top GPA from his school.