No, it's not. Adding a new built-in type that doesn't participate in type-checking in any meaningful way just clutters the language. _Bool is like int, just having unspecified size and slower, since the compiler has to ensure that it shall contain etiher 0 or 1.

Very little, if anything, would have been lost by standardizing "typedef unsigned bool;"

"""No, it's not. Adding a new built-in type that doesn't participate in type-checking in any meaningful way just clutters the language."""

1) It's not about type-checking, it's about reading code.

2) It's not like type-checking is C's strong point.