The answer is yes..! You can add wishList functionality to shopify store. This feature does not comes by default with shopify. But one can easily implement this by using jQuery cookie.
Why wishList functionality needed?
You may ask why it is needed, The answer is so simple. Lets say Pamela is a customer looking for a product in your store, she does not know what are the products you have, she has very less time to explore your products. She might not proceed with checkout or payment instantly. If she want to save her product as wishList such that she can buy it later when she might have more time to explore or checkout, without wishList one can not do these type of functionality. It should turn your visitor into customer as they will always come to your store, and review their wish list items hence buy it.