Are Blameless Post Mortems a Waste of Time?

Recently, at a meetup, I overheard some software engineers talking about a Blameless Post Mortem (BPM) they had recently conducted. They were laughing and joking about a mistake one of them had made. At first, I got the impression that they weren’t taking it seriously. This was something I had introduced during my time at the company they were talking about, and their remarks felt dismissive of…