In C this is because the inline qualifier has at least as much to do with linking and controlling symbol definitions as it does literal inlining of the code int

In C this is because the inline qualifier has at least as much to do with linking and controlling symbol definitions as it does literal inlining of the code into the caller. Relatedly, in languages like C that have global mutable state, it's the callee who knows better whether and when it's safe to inline code, not the caller. Ditto in languages (like C) that can have complex linking semantics, multiple function definitions, etc.