There is a difference between single customer action and collective customer action.
The former puts the "cost" of action disproportionately on a single customer, with any benefit achieved being spread across the many, and of course, virtually guarantees a diffuse effect that will be meaningless in applying enough pressure to bring benefit to begin with.
The owners and players have mechanisms for applying 100% of their collective muscle on a single pressure point. The fans have none. That is the whole point. The "just don't buy their stuff" achieves nothing on a random individual basis.