All programming conferences are C conferences, if you think about it.
I don't see how that follows at all. If you're implying all program languages are derived from C, that's simply false. Lisp is based on the lambda calculus and predates C, as one easy counter-example. If you're implying that all languages run on top of C, that's also false. Theoretical Lisp Machines [0] have been envisioned which do not run C anywhere, and many languages (rust, go, etc) can be built into unikernals t…
I have one at home. It's not theoretically, but factually. About 10000 Lisp Machines had been sold between the late 70s and early 90s. Which probably adds to $500+ million in sales - then.
They actually can run C, but that's usually optional.