x86 assembly doesn't represent the actual opcodes the CPU executes anymore, but it's still the low level "API" we have to the CPU. Even if assembly isn't programming to the metal, it's definitely more to the metal than C, and C is more to the metal than Java, etc. Metalness is a gradient
It would be better to say that "Metalness" is a sort of "Feature Set". IMO, most programmers would tend to agree that C++ is far closer to Java than C is, yet C++ is every bit as low level as C is. Indeed, even a managed language like C# supports raw pointers and even inline assembly if one is willing to get their hands dirty.
There is expressivity and abstraction-ability which are language features, and there is “levelness” or metalness as is it being referred to.
Low and high level languages have two definitions I have seen, one is more objective, but utterly useless: only assemblies are low-level, everything else is high. The other one is more about what can be controlled in a given language’s idiomatic usage, I believe that’s what most people actually refer to intuitively - e.g. C#/Java have ways to manipulate pointers, but you would generally not say that.
In that regard, C, C++, Rust are quite close to the metal with the latter two actually being even closer as they have native control over SIMD datatypes as well, while C doesn’t have that. Note, this is only a partial ordering, as e.g. C#/Java also have control over vector instructions, yet I wouldn’t go around claiming them closer to the metal as C.
Going back to expressivity, C++ is very expressive, while C is very inexpressive, but that is a completely orthogonal axis.
