Most of these stories seem to be from 20+ years ago. Do newer sysadmins just not make mistakes anymore? Or is 20 years the timespan that is needed to get over the embarassment? :-)
I suspect there are multiple reasons, but the increased reliance on cloud DevOps is likely one of them. Truth is that far fewer companies roll their own critical infrastructure these days.
The mistakes made in these comments led to process improvements. Also, the price of computing has come down substantially such that you can actually build highly available and fault tolerant systems.
New sysadmins make mistakes, sure. But they're typically not as critical because recovery processes and correct system architecture insulate the admin from making a mistake with such catastrophic results.
I suspect there are multiple reasons, but the increased reliance on cloud DevOps is likely one of them. Truth is that far fewer companies roll their own critical infrastructure these days.