Why can I not "Create an app loading screen" without service workers? Why can I not "Create an initial app UI to load instantly"? Seems these are trivially possible with regular Javascript, but maybe I'm misunderstanding?
Similarly, "Use push notifications", "Add offline support" and "Prompt installation to the home screen" do not sound like APIs that are dependent on service workers, but I guess they are? (or the article makes no sense)
(By the way, the 300ms tap delay that he gripes about can be hacked away, see fastclick.js)
If you're waiting on async requests than everything is fine without Service Workers, but if you're performing computation then the whole UI will be blocked.