The biggest group outside of numerical computing in Julia land are the PL and systems people though? This includes type theorists [1], database folks [2], distributed systems people ([3] to name just one). There are also a fair number of compiler nuts, hence the existence of multiple projects [4][5] in this space. And this is before getting into things that bridge more than one of the domains above, e.g. [7] or [8].

FTR, I think it's fair to question whether numerical computing should have an outsized influence on the direction of the language. I also think it's a pretty fair comparison to point out how standardized and consistent the Rust governance process is compared to Julia's (the Rust RFC system is an exemplar here). That doesn't mean there is a dearth of PL and systems knowledge in the Julia community though.

[1] https://github.com/AlgebraicJulia/Catlab.jl [2] https://www.youtube.com/watch?v=tRBl-6uEJJE [3] https://github.com/JuliaParallel/Dagger.jl/ [4] https://github.com/FluxML/IRTools.jl, https://github.com/FluxML/MacroTools.jl [5] https://github.com/JuliaCompilerPlugins [6] https://github.com/0x0f0f0f/Metatheory.jl [7] https://2020.splashcon.org/details/splash-2020-rebase/13/Non... [8] https://github.com/JuliaSymbolics/Symbolics.jl