The only way that sort of corporate behavior by Facebook, etc. is to regulate how data about users can be collected and have real (potentially criminal) penalties for data collection without informed consent.
Technical solutions (like preventing side-loading) cannot possibly eliminate the thing driving the behavior; profit motive for stealthily gathering data to build "better" user profiles to lease to advertisers.
Technical solutions (like preventing side-loading) cannot possibly eliminate the thing driving the behavior; profit motive for stealthily gathering data to build "better" user profiles to lease to advertisers.