If this had been some post about lessons learned about a the latest whizbang JS framework people wouldn't have had a second thought.

I've read plenty of her posts and have sympathized, as being a long time sysadmin and learning the exact same lessons. She indeed does have a story telling skill which is sorely needed: ops people tend to suck at effectively sharing knowledge - she's doing valuable work here.

I don't understand why there is criticism?

If I were to be cynical, I'd say it's because a woman writing on information technology. Or because someone is writing about information technology without it being strict and to the point and boring to everyone that doesn't have a geeky interest in that specific piece of technology. But most likely the former.