This isn't too insightful. The article swimmingly explains that there is a "golden ratio" and then goes on to just repeat "you can use that in design", with no concrete examples or explanations aside a small use case for font sizing
The idea is that you can use it anywhere you need to make a decision about proportions. It's not complicated. Designers know that it's no use if you need a proportion close to 1:10 or 1:1, but there is often enough flexibility to use it (say when designing a window or a floor plan.)