"The meandering intro" might be the most common mistake, by far, but the most damaging mistake, by far, is the failure to connect the topic with something the readers are familiar with (anti-pattern #2). Some things simply require a certain level of expertise/prerequisites to begin to understand, but I've repeatedly seen in software blogging, READMEs, etc. a failure to answer "what is this, compared to what I'm familiar with, and if I'm not familiar with anything relevant, why should I want to be?"

This applies to almost everything in the software space. New tool? New design pattern? New library? Language idiom? Language? Or, for more modern takes, new model? New harness? New harness option? New use pattern? Give a brief summary of what a project looks like without it, to convey the problem that its existence alone is solving. Then go into the details of how it might compare to other solutions.

Maybe it's just a specific way of how my brain works that finds this sort of information intuitive, and the lack of it particularly annoying.