Both of these features are available in browsers these days.
It basically is just a difference in use case and how most people thing about "apps" vs. "websites". If I have a long term relationship with a business, and I access its functionality frequently, I'd rather have it as an app on my homescreen.
There are benefits to having something installed. You can give anything installed the ability to send notifications.
Having to manage that permission on a per-website basis is way above the tech ability of most users.
But this is apparently difficult for "tech literate" people to grasp.