[2023] Can you just let me whisper myself as much as I want please?

I can shed a little light on why this is: While you are only messaging yourself, all whispers are still messages going through the server, regardless of whether they are going right back to you or to someone else. The rate limiting is also a protection mechanism for our system. (Incidentally, I will often pop into my home instance and use say chat in there for things like this.)