A couple more pull quotes:

"... at Etsy. We instead want to view mistakes, errors, slips, lapses, etc. with a perspective of learning. Having blameless Post-Mortems on outages and accidents are part of that."

"an engineer who thinks they’re going to be reprimanded are disincentivized to give the details necessary to get an understanding of the mechanism, pathology, and operation of the failure. "

"A funny thing happens when engineers make mistakes and feel safe when giving details about it: they are not only willing to be held accountable, they are also enthusiastic in helping the rest of the company avoid the same error in the future."

My favorite quote: "[Engineers who make mistakes] are, after all, the most expert in their own error." 

I can honestly tell you that I've been the person who has primarily been involved in multiple incidents that were followed up with a postmortem. Each time it's been a great experience. There really is no blame. It doesn't even enter the picture. Each time we've learnt and improved the situation so that the same problems don't arise in future. Everyone wins.