it's fine to require service workers if it's justified
I don't agree with this because you're essentially defending writing websites and apps for specific browsers. "Oh, this doesn't work in your browser because it requires [specific tech|devs to test in more than one browser|whatever]" is a lame excuse in a world where progressive enhancement has been an accepted approach to developing web software for twenty years.
As a tech demo to show something is possible it's fair enough, but in the real world this shouldn't ever happen.