The thing is, in the MCU, there's seldomly any big threat in the individual heroes' movies that require more than the intervention of the title hero. Marvel has been saving the Earth shattering threats that are too big for a single hero to contend with for the Avengers movies. Either that or the threat can really only be dealt with the title hero, like magic based threats in Dr. Strange, or the threat is only after the title hero and doesn't care about much else. It's really mainly in the comics that are guilty of dealing with major events that threaten the Earth but is only handled by the hero, or heroes in the case of the X-Men and related titles, and not every hero on Earth.
At the same time, this also varies depending on the hero. Some heroes, like Batman, tend to deal with villains that are Gotham based and aren't interested in taking over the world or anything like that. Plus his rogue's gallery is made up of mostly non-super powered villains. With the exception of Ras Al Gul, few of any of Batman's rogue's gallery is of any threat outside of Gotham.