Why isn’t <input type="date"> used more often?

HTML natively has a date input:

<input type ="date"/> 

(Codepen here: https://codepen.io/dwjohnston/pen/zmwRQV).

It comes with a date picker etc.

However, I've just noticed that I don't usually see it. Usually websites either get you to enter your own slashes into a textbox, or select from three dropdowns.

Is there a reason that this isn't being used?