If you didnt already know it,James Gunnis big on coherent narrative.
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Thats fine if it doesnt disrupt the story, Gunn wrote.
Its the plot contrivances that develop from a cameo, not the cameo itself.

James GunnGilbert Flores / Getty Images
If a character is in film, they have to have a reason to be there story-wise.
Its normal for single protagonist films to have other characters much more unusual for them not to.
He also pointed out that none of those roles [inLegacy] are cameos.

Oppenheimerwas presented as an example of a single-protagonist film with a lot of characters.