Or you could look at it as those companies have so much money and fame that they have tens of thousands of candidates pounding at their door so they can afford to arbitrarily reject approximately everyone.

But if you're running a startup (target audience of ycombinator), you'd do well to play a smarter game since you can't outspend or out-fame the FAANGs. A big part of that is to have better interviewing practices than they do.