On the other hand, just working at big tech doesn't mean you are especially great. Conformance and criteria other than raw skill matter. As you say, promotion games, etc... I would just lump all of that under conformance. So, you aren't wrong.

However, why startups outperform big companies isn't just the skill gap. Even if you have the most amazing leadership in big tech it is monumentally difficult to move the needle on some problems purely because of size not because of incompetence. All I am saying is don't overindex on perceived intelligence. A big org can start looking pretty dumb even though it is still far right of the bell curve compared to even a startup (hypothetically). Org size and the constraints that brings are a significant factor.