> Quite a few big tech companies are either actively doing much of their new systems programming in Rust, or else dipping their toes in

I don't think that's true. It seems to me that a lot of people believe this simply because a lot of other people believe it. You see it everywhere. "Oracle rewriting MySQL in Rust". "Microsoft rewrites Skype in Rust". "Linus Torvalds rewriting Linux in Rust". I have yet to see proof of any of it.