They can block the like buttons and such (especially since the browser has built-in share buttons) while leaving the content-related resources alone.

I have all the uBlock lists enabled (social blocking, anti-facebook list, annoyances, etc) and don't notice any breakage or missing content unless I go and look for it explicitly (like blank spaces where the like buttons should've been).

Surprisingly, both Google and Facebook themselves actually seem to work fine (at least they load if I allow them on the firewall, don't have accounts to test thoroughly) so it wouldn't prevent people using the sites themselves, simply block their trash like buttons and similar garbage they polluted the web with.