I agree that the beta label needs to stay on the Site Editor a while longer. When Gutenberg was released, I used the Classic Editor on all my websites for about a year, because I was worried about the editor breaking or features not being available.

When I checked back on the editor's progress a year later, I gradually started using it on all my websites without any major problems.

I hope with the Full Site Editor that it will always be an opt-in feature, since many of my websites only have myself as an administrator, so a drag-and-drop interface would not be needed.