"Public on the web Anyone can find it on the web. Search engines will find the doc, giving it a larger audience."
It's not unambiguous. It's very clear. The only way you can't tell what it's doing is if you just pay no attention whatsoever to what you're doing. It's not the default sharing method from either Office 365 (web, traditional or Android/iOS) or OneDrive. You have to opt into using it at all at an IT department level if you have a corporate Office 365 department. You really just can't stop users from footgunning themselves when they're on the open Internet.