Disallow sharing with links

We currently run Sharepoint Online sites as intranets. Now we'd like to also use Sharepoint sites as an extranet for the collaboration with external users. 

We are using community sites in our test enviroment. Sharing the whole page and put users in the three permissiongroups (owner, member, visitors) is exactly what we want and allow very easy access management for the enduser. Unfortunately the "sharing with links" (share only specific files and folders) is a thorn in our side, since this results in a big mess in our usecases. Is there a way to disallow such behavior and only allow sharing the whole site with the "Share this site" button?

Thanks in advance for any help.

Patrick