Its all readily googlable, certainly. My point was that its poor practice when writing a piece aimed at introducing people to a subject; if they have to go to google every few lines to see what something means, that distracts attention from what the article is actually trying to convey. For that matter, they could just as easily google for a different article.
Your confusion stems from what kind of beginner the author means. You read it as "total beginner to anything vaguely related to microcontroller programmer". I assume the authors means it as "has programmed stuff with microcontrollers before but never made a hardware design from scratch yet". After all, picking a microcontroller is a design/architecture choice more than a programming choice.
Well, then there's another term he ought to define! :D I've done several projects using various flavours of Arduinos and Pis, but that sort of hobbyist-maker-level experience hasn't lead me to encounter an acronym for "Bill of Materials."
Few people have seriously contemplated ordering the manufacturing of a small run of something they themselves designed. More people have seen the term BOM when reading estimates of how much it costs big brands to manufacture a smartphone or a game console in industry publications or even in the more technically-oriented consumer reviews.
