That does not contradict what I said. When choosing the type, all you need is a type that has at least the range you require, and the basic types give guaranteed minimum ranges.
The only advantage to choosing an exactly-N-bit type over an at-least-N-bit type is possibly saving some space in very large allocations. In most cases this won't be important - and when it is, the mininmum-width types from stdint.h (eg int_least32_t) are more apropos than the exact-width types.
The disadvantage is the impedance mis-match with all the existing libraries of code using the basic types.
You should know the range of values that you are expecting to be holding in an integer, and choose the type accordingly.