Modern browsers have the capability to auto update themselves. In Chrome (as an example) you don’t find yourself manually updating the browser version, it just happens magically. While you can go ahead and disable this feature, most common users will not do this. Continuing with the Chrome example, this means your stable browser version changes every 6 weeks or so. As an application developer this is a nightmare.
In many WebRTC use cases I hear about from customers, the need to alert the user is a mandatory requirement. They are looking for WebRTC Push Notifications services. With the current work being done in the standards along with the actual implementations already available, it looks like this requirement is going to be satisfied. This work is not specific to WebRTC