Yes, perhaps I should have clarified. BR can only use the veto to make a HIRE to NO_HIRE decision. He doesn't have the veto to make a NO_HIRE to HIRE decision.
Source: Am bar raiser.
While bar raisers can't make hiring managers take a candidate they don't want, they can absolutely "veto to hire" for Amazon.
It just means that Recruiting needs to find another team, which the candidate is not guaranteed to be interested in. And that team's manager will also want to interview the candidate, so an offer is not guaranteed again.
What I think is more likely is that managers are ready to take 90% candidates with hope of grooming them because they have a fallback if it was a wrong decision. Which is a positive thing in my 2c opinion.