Solving all of the edge cases causes exponential blowup of scope.

20% of the cases cause 80% of the work.

Subtraction cannot be done by consensus.

When people on a team hear an edge case everyone by default assumes "of course we want to fix it".

It takes boldness to say, "no, we will not fix that, we will cut that case out of the scope."

It requires someone who everyone on the team agrees has the authority to be the authorial voice of the project, to take responsibility for the outcomes.