Why is it not a silver bullet?

The primary (only even) cause of the climate crisis is the fact that we have burnt and continue to burn a ton of carbon and emit it as CO2 in the atmosphere. And as most of the world functions with some form of capitalism, it makes a lot of sense to put a price on something to make it less desirable. In fact it makes so much sense that until we have put a significant price on fossil carbon use we cannot tell our children that we really tried to do something to prevent this crisis.