Certainly true, and I do think people skipped the section on refactoring. But I guess my real complaint here is that the article itself seems to advocate against the principle of charity!
Asserting that generic versions and frameworks are inherently 'red flags' that someone doesn't know how to do their job doesn't seem like an inducement to more reading, it seems like a misleading absolute. I got that feeling throughout the whole piece, for instance with the implication that memory limits are key in all tasks.
It was either very domain-specific advice (I know the author came out of game design, which fits his list better than general software), or vastly overstated advice.
I don't think they're being introduced as red flags to say "call bullshit on this and don't do it" but to be aware in the following cost-benefit analysis.
It will always be possible to accuse an article or even a book of being light on details. It is after all some pointers and not a scheme to make a non-technical manager technical. Learning anything takes more than reading at surface level, particularly of a clearly introductory article. The principle of charity goes a long way to smoothing out the inner pedant.