The visible watermarks primarily aim to deter unauthorized use rather than to prove copyright claims or help people locate a copyright holder. If you want to pr

The visible watermarks primarily aim to deter unauthorized use rather than to prove copyright claims or help people locate a copyright holder. If you want to prove copyright claims, there is a centralized registration system that has existed for over a century https://www.copyright.gov/registration/index.html https://www.copyright.gov/registration/index.html Locating copyright holders is a much thornier problem https://en.wikipedia.org/wiki/Orphan_works https://en.wikipedia.org/wiki/Orphan_works but it's not obvious that a decentralized database is more effective somehow than a centralized database.