IMO the cognitive load of Rust is different in practice just from basic nuts and bolts things like having a ecosystem of libraries that culturally emphasizes things like portability and heavy testing, and a standard package manager and an existent module system (C++26 fingers crossed). I dislike Cargo but it's incredibly effective in the sense any Rust programmer can pick up another project and almost all of of the tools instantly work with no change. I mean, Rust is frankly most popular in the same space Go/Swift et cetera are, services and application layer programming, where those conveniences aren't taken for granted. I see it used way more for web services and desktop/application services/command line/middleware libraries than I do for, like, device drivers or embedded kernels. Those are limited enough in number anyway.
Really, the ergonomics of both the language features and standard tooling meant it always meant it was going to appeal to people and go places C++ would not, even if they in theory are both "systems languages" with large surface areas, and they overlap at this extreme end (kernels/embedded/firmware/etc) of the spectrum that little else fits into.
Really, the ergonomics of both the language features and standard tooling meant it always meant it was going to appeal to people and go places C++ would not, even if they in theory are both "systems languages" with large surface areas, and they overlap at this extreme end (kernels/embedded/firmware/etc) of the spectrum that little else fits into.