Why load CSS asynchronously? All stylesheets are render-blocking by nature. Meaning that referencing CSS stylesheets with <link rel=”stylesheet”> causes the browser to stop parsing the HTML and wait while a stylesheet loads. This is bad for performance and will trigger warnings on all page speed tests.
In this day and age of short attention spans and demand for instant gratification, page speed is crucial. Not to mention that it’s one of the ranking factors on Google.
Progressive enhancement – the fancy term to describe a process for developing modern websites and web apps. I’ll try to explain it how I understand it. So hopefully, next time you see it you’ll know what I’m talking about.