Would this fix things completely? Not anymore than ARIA guidelines fixed accessibility. But establishing best practices would change the narrative around privacy in a positive way.
Companies like Facebook would not be described as 'groundbreaking' or 'predatory' (depending on whose side you're on), but as being competent or incompetent in anticipating and understanding privacy.
The social network of the future: No ads, no corporate surveillance, ethical design, and decentralization! Own your data with Mastodon!