The fact that original C "inline" was designed in same "permissive" way and is almost unused in practice (as opposed to compiler-specific force_inline attributes) does say something.
Do you mind to back up your "fact" with some numbers? Afaict 'inline' is more common than __attribute__((forceinline)). (Well ok for C code #define is even more common, but most C code is stuck in the 70ies anyway so that doesn't mean anything.)
