Why does BitArray not provide type guarantees about size of the array?

[rkshthrmsh]

Could someone please explain why the following code passes compilation?

type Example = BitArr!(for 4, in u8, Msb0);

let example: Example = bitarr!(u8, Msb0; 0; 7); 
// Why is this allowed? Because type is supposed to be restricted to 4 bits.

let example_1: Example = bitarr!(u8, Msb0; 0; 4);
example_1.set(7, true); 
// Once again, why is this allowed? Because type is supposed to be restricted to 4 bits.