The idea that local events would not be a determinant factor in travel planning ignores the major downsides they can cause. Before committing, one must always consider the exit conditions in case of problems; a major event can make a destination unfeasible.
The risk of a surge in accommodation costs and unmanageable crowds is not a simple nuisance, but a potential failure point for a trip.
For example, ending up in Blankenberge during the Wind Festival without a reservation guarantees paying triple for a room or sleeping in your car.
It's not just a matter of adaptation, but of the very viability of the stay.