Use cases for aria-relevant?

Does anyone know of any examples of aria-relevant being used in a helpful
way in shipping software?

I have concerns about this attribute. The PFWG originally added it to ARIA
because theoretically a screen reader should be informed about any changes
and be able to receive hints on whether those changes are useful. What
happens when a user leaves a chatroom and their name is removed from a
sidebar list? It seemed bad to develop a standard where it wasn't even
possible to have removals of content be presented.

The default, aria-relevant="additions text" is to speak content being added
and text changes. This is by far the most useful value, and I'm not sure
any other value has ever been used in real life in a successful way.

For any other value to be useful, we'd need to know that AT/Browser
combinations have been tested and provide a useful experience. For example,
is a user informed that the element was removed? Or will the screen reader
just read the element the same way it would have if the element was added?

I'm pretty skeptical of the real-world value of this attribute and wonder
if it's causing more harm than good, as authors may not understand what it
does, and implementations may not all treat it the same way. (For example,
Mac Chrome and Safari are not treating aria-relevant="text" exactly the
same for live changes that insert an entire text node).

Right now, it's almost certain that if an author used this attribute it was
because they were confused by its purpose and maybe thought it was a
helpful bandaid for fixing a bug, and it probably wasn't.

Thoughts?
Aaron