I could use (and have used) Körber/HighJump Advantage Architect in production, and yet that's nonetheless so far from notable that Körber's own Wikipedia page doesn't even bother to mention its acquisition of HighJump and the software products thereof, let alone the proprietary graphical programming language which HighJump's customers use to configure and customize their flagship warehouse management system.

Needless to say: production use ≠ notability, for very good reason.

From Cambridge dictionary:

obscure (adjective)

not known to many people:

- an obscure island in the Pacific

- an obscure 12th-century mystic

Why does its use in production matter? Perhaps the syntax itself is obscure, but we're not discussing syntax but general awareness. Anyway, the most common "real" use of brainfuck is to prove Turing completeness of other things by finding a way to compile them into brainfuck.