Before committing, it is crucial to consider the failure risks that local events pose to a destination.
The idea that it is just a "component" is an optimistic point of view that ignores stop conditions.
Take Bruges and its Procession of the Holy Blood: if you haven't booked months in advance, it's guaranteed you'll find nothing or pay the high price.
The mandate is to protect oneself from bad surprises; a major event can make a trip impractical, even if it is technically a "part" of validation.
This is the only way to avoid drawdown.