People use websites for several important tasks such as banking, shopping, entertainment, and paying their taxes. In doing so, they are required to share personal information with those sites. Users place a certain level of trust in the sites they share their data with. If that information fell into the wrong hands, it could be used to exploit users, for example by profiling them, targeting them with unwanted ads, or even stealing their identity or money.
Very informative! I had come across some of the settings mentioned there, in Firefox hardening guides but never understood what they meant until now.