This is by choice, while it is really convienient to interrupt execution flow by throwing an arbitrary value, it's extremely hard to know whether calling library code can throw, and if yes, what kind of errors, without exceptional documentation.

The Result<T,E> type is very explicit, and can be easily ignored, composed or "re-thrown" with the "?" suffix without nested try/catch blocks. Return value based error handling is something Go, Elixir and other more functional languages have also adopted.

Panic is there to aleviate the really exceptional circumstances, when the trade-off for possible program termination is worth the much simplified error handling, such as when casting to a smaller integer type in case of overflow, or locking a mutex when it may be in a posioned state (which, funnily enough, can arrive when a panic occurred whilst the mutex was previously locked, i.e. the mutex guard is dropped during a panic).