The point is exactly that the "concept" of what the template should do is informal and a careful, detailed specification in a far more expressive language than

The point is exactly that the "concept" of what the template should do is informal and a careful, detailed specification in a far more expressive language than vintage C++ would be needed to elicit good compilation errors from something like vector<bool>. Proper parametricity is only a starting point: types that specify alignment, equality and lifetimes would be needed to make it useful.