> I'm sure I'm just a number to make sure the hiring manager passes some internal threshold so that they can hire the person they want anyways
This is definitely not the case, because we don't have hiring managers (at least in engineering; there are parts of the company that this post doesn't apply to). The system has been designed to definitively prevent that sort of thing from happening. Nobody can say "I want that person" and hire them. You feed people into the hiring pipeline, they get interviewed by a series of calibrated peers, and then a separate committee of people who have never met the candidate reviews the interview feedback. There is no way for any single individual to get somebody hired. This largely removes personal biases from the outcome.
As for your own experiences, the key thing to understand here is that our hiring processes are designed to have a high false negative rate and a near-zero false positive rate. It is explicitly a goal to pass up on many capable people in exchange for not hiring any bad ones. It's not perfect, and there are ways in which people are working to improve the system, but for the most part it's doing what it's designed to do.