Here is how it explained in the docs: https://docs.rs/ractor/latest/ractor/actor/index.html#actor-...
To me, your supervision tree should be dedicated to that purpose and forms a superstructure relating entirely to spawning, resource provisioning, restarting, shutdown. Part of what makes it nice in Erlang is that it's consistent and thoughtless, just part of designing your system instead of being behavior you have to write or worry about much.
Here with Ractor they've built a special monitoring channel and callbacks into Actor (`handle_supervisor_evt`). This implies at some point one might write a nice supervisor in their framework that hopefully has some of those properties.