What motivation(s) does Stack Exchange have for social media sharing?
- To enhance the experience of the person viewing the page?
- To increase the number of people visiting Stack Exchange?
If the motivation is number 2, then I could see why it's not possible to turn off social media sharing. We need more people in the community, and more people viewing our advertising, whether you like it or not!
If the motivation is number 1, then the main reason not to make it configurable would be that it means more work for the developers, and one more thing for users to configure.
Background: Hide all those damn social buttons and links!