Both positions have their merits, because it's not so simple to say whether local events are always key to choosing a travel destination, or if they are systematically secondary.
I believe that a middle ground is necessary and that their importance varies greatly, heavily dependent on the context of the trip.
For example, for a couple planning a honeymoon in Saly, the Saint-Louis jazz festival can be a major attraction influencing their schedule.
But if a Dakar merchant goes to Touba for the Magal, the dates of other tourist events will have no impact on their essential travel.