Flamestrike
Legend
I don't see how that makes it the default setting. APs are additional purchases not included with the Dungeons and Dragons game (PHB, MM, DMG). Perhaps, instead of giving examples, it might be more helpful to propose a definition of what a default setting is.
Because that's the setting DnD defaults to when they write adventures.
Its also the level of magic and power on parity with the level of magic and power possessed by the classes as presented in the PHB.
A low level Fighter (T2) can literally beat a T-Rex with a rusty knife in ANY setting. Most classes can take one down at that level, That's not low magic or gritty realism. That's a superhero. Thats the classes as written.
Reflected in the settings (which mirror this kind of high magic superheroics).
DnD (RAW alone) is not low magic or gritty realism. Its borderline gonzo high magic (as are all it's published settings to date). Most have flying cities, a history of magical WW3, Gods walking the earth, interdimensonal and outerspace travel and more.