there's a strain of management books called "Topgrading".
The gist is: you, the new founder, are grade A awesome, and you can have a successful company if you only hire other As. Unfortunately, Bs and Cs will show up, and lie about their work history! So you better scrutinize their resume line-by-line. The books teach intimidation tactics meant to flush out inconsistensies in self-reported work history. In reality, it becomes interrogation-style focus, trying to highlight "problems" of any kind.
That's not a rare attitude ("I never hire unlucky people"). I'd imagine that VCs are the same way.
Yes, you'll exclude good people if you cop that attitude, because good people often get unlucky. However, the people you get will be terrified (and manipulable). The purpose of back channel reference checking (or age discrimination) isn't to get good people. It's to scare the shit out of the people you have, so they do what you say without question.
Can you elaborate? I'm curious; I may have dodged a bullet here.