younger - lack of experience
female - women to the rescue
international - lack exposure to local customs
"Fresh perspective" / "leaders in the decision making process" (leadership positions) - Hacker News agrees that "it's all about execution" and that "adding more ideas/perspectives" as you suggest here might be rather counterproductive or at least not a benefit.
It's software engineers that get payed a multiple of other (regular) jobs in silicon valley, which sets SV apart from the rest of the world.
People arguing like you are either young, not-male and/or not-native and want one of the financially attractive leadership positions for the money. They don't want or promote diversity anywhere else but in this limited area (leadership positions), which just quickly exposes their true underlying motivation: Hypocrisy and your own greed.