Are there any downsides to choosing not to join threads in Rust?

Question

I have a program that uses multiple threads to brute force the decryption of some encrypted string. The main thread has a channel, and the sender is cloned and sent to each thread. When a thread finds an answer, it sends it to the receiver which is in the main thread.

In this program I am not joining the threads, instead I use the blocking call sender.recv() to suspend the main thread until a single other thread finishes.

My hope is, once this call finishes, the main thread will return and all the other worker threads will be terminated.

Is this a poor design choice? Are there drawbacks of not having some condition in the other threads which would cause them to return when the solution has been discovered? Is it okay/safe to rely on the compiler to clean up my threads before they've technically finished?