Thanks, Revanth Kausikan for the question you asked. The essence of this article is to illustrate and make clear what mutating function means in Swift. It does not mean that you can only set the value of struct properties through the mutating function only. You could create the instance of the struct and have access to its properties to modify it the way you want.
However, in the example I used in the article, my intention is not that you could modify the struct property through its instance. You can only modify the struct property through the exposed functions. I have modified the access level for the property to reflect what I actually wanted to pass along.
I believe this clarifies the question you asked. Thanks.