The idea that a destination validation process should always consider the impact of local events as a major component is a very broad generalization.
Honestly, who really benefits when we insist on this point? Often, it's travel operators or event organizers who have an obvious conflict of interest.
For most of us just seeking some peace, like a weekend on the Belgian coast, the small shrimp festival in Ostend won't change the game if hotel prices are reasonable.
The true decision driver is much more often the weather, the cost of accommodation, or ease of transportation, not an event schedule.