Answer:
The reason for this is that putting out the fires only postpones the fire outbreak to a later date, and there is the fear of the fire outbreak being more sever when it actually comes.
When wildfires burn, they clean up the forest off dead trees and falling logs. Also dried leaves and twigs and unnecessarily dense vegetation is cleared up by the fire. These materials are the main fuel of these wildfires. Putting out these fires, especially those that start naturally means that these fuel that should be cleaned up are allowed to accumulate so that when the fire actually happens, it does so with an unnatural intensity. Also, when fire burns, the ashes that are left act as nutrition for the forest, and the forest is allowed to regrow; reborn from the ashes. The only cases that might need human intervention is when the fire is human caused or due to human activities. Natural causes of fire can be due to a very high temperature, lightning striking a tree, etc.
