PP could have been more clear and say syntax-rules (note the dash), which means macros. Macros are usually considered an advanced topic.
Given that most languages don’t have syntax rules or anything like it, I’m gonna go out on a limb and say that most language introductions/overviews/tutorials don’t mention it.
In fact, what languages can you say do not have syntax rules?
Since macros are a very important part of Racket, complaining that a friendly introduction mentions them is [insert non-friendly characterization].