There are countless details and aspects of a shared-continuity universe spanning several different campaigns, goals, and styles. While the shared-continuity approach is emblematic of the source material (comics, and the Marvel Cinematic Universe), it is entirely optional.
Every action a superhero makes has a widespread impact across cities, countries, the globe, and even the galaxy. That is the burden they carry when they try to save the world. That influence that heroes wield is important to give campaigns in Absolute Overpower weight, especially across multiple campaigns with several Narrators. It also helps players realize the gravity that they possess.