Comment by dragonwriter

> There is a significant constituency for "curly brackets {}" and "square brackets []".

Yes, but there is still basically no constituency for “parentheses” (“{}”) or “parentheses” (“[]”), except in some narrow specific contexts; in programming, one example would be discussion of certain Lisp dialects where either all or certain uses of “()” in classic Lisp can (or, in the “certain” case, sometimes must) use the others, in which context “parentheses” are sometimes used generically for all three.

So, while there is a variety of ways paired delimiters are described by native speakers, the particular use here was still outside of the normal range of that variation.