The biggest impediment to much larger participation in the top tiers of software engineering is imposter syndrome and the elitism of the industry when faced with a trainable candidate. Every startup aims to hire someone who can "hit the ground running" and who doesn't need an assist from anyone.
Also, the largest tech companies have chosen to use LeetCode-like problems almost solely to assess candidates, which are unlike most tasks done on the job most days. These tend to select for people who trained specifically for the interview and for coding competitions, such as ACM.