I find this characterization of a value type based on its implementation details rather than its observable characteristics to be both confusing and unfortunate

Surely the most relevant fact about value types is not the implementation detail of how they are allocated, but rather the by-design semantic meaning of “value type”, namely that they are always copied “by value”.

I blogged a while back about how “references” are often described as “addresses” when describing the semantics of the C# memory model. Though that’s arguably correct, it’s also arguably an implementation detail rather than an important eternal truth. Another memory-model implementation detail I often see presented as a fact is “value types are allocated on the stack”. I often see it because of course, that’s what our documentation says.