We know more backstory is ahead in Captain Marvel, which is set in the 1990s, and more tie-in answers will follow that in Avengers 4.
It also seems to be the explanation for why they haven’t called Carol Danvers every time the Avengers have faced major threats.
The new comic goes into greater detail, but at least we have an official Marvel explanation for why Captain Marvel was the last resort instead of the first call.
Well, whoops, ’cause he did have to call Carol Danvers/Captain Marvel.