Original author here, I agree the depths of abstraction in CS are endless. But in todays day and age, it seems like SQL has matured enough to be learnt without too much background in CS
But it's also overkill for many problems requiring persistent storage. If I were teaching a programming beginner how to save data for a program to persist across invocations of the program - there are tools I'd reach for before saying "well, first we need to install MySQL or Postgres, then the db abstraction libraries, then we need to talk about ORMs … ". Pedagogically, going from variables to hashes to tied hashes to NoSQL is a relatively direct progression - at least to me.
Having said that - there's an enormous amount of PHP ( and Perl and …) code out there showing beginner programmers getting shit done with minimalistic but workable understanding of SQL.