Design is not just what it looks like and feels like. Design is how it works.
I can't call myself a designer yet but I am learning.
I do think design applies to everything I am doing. Even this wiki has some design choices of how it can be structured. As the quote above says, it's not how it looks like, it's how it works.
Thus I try to be conscious of how my design decisions affect what I do. I like to use Sketch and Figma when designing things.