Below is the text taken form MIT OCW 6.170
Why would a language have immutable types? Because aliasing is complicated, and when you use immutable types, the issue doesn�t arise. Also, code built with immutable types can sometimes be more efficient.
Where aliasing is defined as two reference variables pointing to same object.
So we can have aliasing that is two reference variables for same immutable object so i can't understand why "the issue doesn't arise".