It could be considered a non-modal version of window.alert(), which is the only option available to quickly display a message on the website instead of the console. The problem is that alert() is a very intrusive blocking operation.
Currently there are many popular libraries like react-toastify trying to solve this lack, but they require a lot of javascript.
Additionally, a shared UI across browsers would allow users to identify and recognize notifications more easily.
I open this thread for discussion. If someone wants to be champion, it would also be very useful.