For browser based apps and possibly campaign sites (obviously when you say it's ok) this could be great. Though I would imagine the "add us to your home screen" nag will become even more prominent and a lot more tedious.

"One of the web’s superpowers is its low friction". I see the unscrupulous making it rather abrasive.

Not going to say use with caution, but be mindful of use.

As web app developers - not native android/iOS developers - our decisions on how to achieve certain goals has always been held back by not being able to use push notifications.

Great to see a standard developing on how regular websites can start to implement push notifications, opening up a lot of interesting mechanics.