I agree. I am not an advocate of tying up a dog.
I can’t remember the exact words, but I read once that a tied dog just wishes for freedom, and will run at the opportunity, but a free dog just wishes to be home.
Tied up dogs become aggressive because of being paradoxically terrified all the time.
They’re not stupid; they *know* they’re helpless targets for any manner of threat to their life.
They know they’re trapped.
All animals operate on ‘flight or fight’.
When you remove the “flight” choice with chain, only “fight” is left...so they do.