Whispers expire & self-delete after a certain time.
The idea would be whisper messages delete like snapchat.
Currently users can be baited into whispers from people in their chat who "want to help" if there's some sort of issue.
They then have your username in their whispers regardless of blocking.
So if you experience trolling, harassment or stream sniping this is still very doable regardless of blocking. Any username change appears as if they are unblocked.
After sending a messaged to support I received the typical response and directed to managing harassment.
Again i point to the above...Even if you block someone and change your name it's still viewable in their inbox.