Apprise isnt exactly aimed at you as a user, but more at someone who makes their own project.
For example you make a tool that notifies a user about available updates of Docker container images. Users want you to include email notfiications, and Pushover, and Pushbullet, and so many more.
Instead of you manually adding each platform as its own, which takes a long time, you can simply add support for Apprise. And Apprise covers all those platforms already for you.