When you share a document link to Watsaap or any other app, there should be a mandatory option available to set password and also expiry of the link. Since the option is mandatory, it will add a security. Phones some times hangs and process overlap . Sometime the link you send can go to uni red parties. If you have a password you can still secure documents. In one drive you carry many financial and legal data. Basic security has to be provided to all paid and unpaid users. An app Like one drive should not charge for security of documents.