@shiri I know that public posting means it's readable to anyone on the Internet who finds it. But as long as it's on Mastodon, I still have controls to edit and remove things as necessary. My account being mirrored to another service without my consent removes the ability to control my content.
And besides, the right to reproduce a work belongs to a copyright holder. All it takes is one person who can afford to lawyer up and this becomes a prohibitively expensive lesson in copyright law.