How does that happen? The way interviewing should work is that every person that interviewed you should vote, and if its unanimous that you should be hired, then some SVP a few levels up decided to veto it, I'd be livid if I was a hiring manager.
So, your described situation almost never happens. There are candidates who get 100% hire votes, and they get hired. Most candidates have some variability- it is rare that everyone is 100% onboard. The svp review is to make sure that the hiring process has worked and nothing major has been missed.
If you so lack in trust that the people on your team can make good hiring decisions, even to the point of rejecting somebody you haven’t actually met...well... that’s just nuts.
My theory was that it was a comp/background mismatch. I was interviewing for a role that someone with more of a sysadmin background could do but I had a SWE background and was trying to command that comp level.
For many (although not all) people being hired at Google, the SVP approval process happens before you're matched with a manager. The SVP approves you to work in their PA, and then you're matched with a manager within the PA.
They are free to do so, but when they do it for arbitrary reasons, it instills a lack of trust in leadership. Leaders that lead through fear are much less effective than leaders that are able to motivate their followers in positive ways.