Sometimes the seesaw of web tech is fascinating. Service workers have arrived, and beyond offline networking (read Jeremy's book) which is possibly their best feature, they can enable push notifications via the Push API.
I totally get the push (pun intended) to make that happen. There is an omnipresent sentiment that we want the web to win, as there should be in this industry. Losing on the web means losing to native apps on all the different platforms out there. Native apps aren't evil or anything — they are merely competitive and exclusionary in a way the web isn't. Making the web a viable platform for any type of "app" is a win for us and a win for humans.
One of the things native apps do well is push notifications which gives them a competitive advantage. Some developers choose native for stuff like that. But now that we actually have them on the web, there is pushback from the community and even from the browsers themselves. Firefox supports them, then rolled out a user setting to entirely block them.