It's not like you're being force-fed notifications against your will. And it's not like offline content hurts you. Any inconvenience offline support causes to you pales in comparison to how much people benefit who actually need to be able to access content on spotty connections.
But for notifications, even the only-once* prompt is an annoyance we never had to deal with before. It's like the European Cookies Law: great in essence, but when every website bugs you about it then the problem has been exacerbated, not solved. I don't care about receiving notifications for a website I visit once in a blue moon, and I especially don't care to be even asked. There should be an action that triggers the prompt, like some kind of opt-in.
Edit: same with "app banners"
*it never is, because cross platform, multiple devices, multiple browsers. A fucking pain.