Why exactly is the leaky tech pipeline a fallacy? I see it claimed as such frequently, but then I see other SJWs argue it is the biggest thing that needs addres

Why exactly is the leaky tech pipeline a fallacy? I see it claimed as such frequently, but then I see other SJWs argue it is the biggest thing that needs addressing(I think I recall a big-shot diversity person at FB saying the pipeline needs to be fixed, and a big-shot diversity person at Google say the pipeline is a distraction). To me, it doesn't make sense how the pipeline couldn't be a major issue. I took an intro to programming class in 9th grade (1999), and there was literally one girl and 29 boys. How can you ever overcome that and hope for a 50/50 split at the end when, for whatever reason, 14 year olds choose such drastically different paths based on their genders. And I know for a fact that no one took the class or didn't take the class because of the demographics of the GCC steering committee.