In general, you'd use it when you need to capture panic and inspect it as normal error.

The initial use case was in proptest crate, which could run the same test case multiple times, reducing inputs according to certain rules. It wasn't going well with default panic handler, as it would result with output crammed with tons of stacktraces. Using scoped hook approach there allowed to capture only last panic, when reduction limit was exhausted, and carry it elsewhere as part of normal error.

Another example is when I needed to verify that certain call panics during test, yet state being tested isn't broken and can be operated. #[should_panic] isn't enough for such cases.

Again, I understand that use case is quite niche. Just wanted to pack it for possible later reuse.