Keep sharing available, but govern it per site. SharePoint is designed for people to work with shared information. Turning off sharing everywhere recreates file-server friction, while allowing every user to share every item can create access that nobody can explain or review.
Permissions decide who can access content. Ownership decides who is responsible when access, purpose, protection, or lifecycle needs to change.
A SharePoint site is a shared place with a purpose: for example, a department site, a project site, or an intranet area. It contains the information and controls needed for that purpose.
Opening a SharePoint site starts more than one action. SharePoint identifies the visitor, checks whether they can open the site and page, and lets each web part retrieve content from its configured source.