I disagree. If you’ve run a mailing list of any reasonable size before you’ll quickly run into the same experience the author had: you have to get good at a lot

I disagree. If you’ve run a mailing list of any reasonable size before you’ll quickly run into the same experience the author had: you have to get good at a lot of disparate skills in order to keep the list from falling apart, either due to user attrition or technical reasons like spam traps and engagement metrics. The OP didn’t pitch this as an exhaustive reference of every issue that can come up, but it’s a good sampler of the kind of problems you have to deal with, and stuff that most people wouldn’t even think about.