I never heard that natural old growth forests need wild fires.

Fire adapted ecosystems abound. Pretty much the entire Sierra Nevada for example. Most if not all coniferous forests. Prairies and Savanna. Some species need fire to propagate and survive.

Fire good.

It depends on the forest, but there are fire adapted forests that benefit from fire. We’ve completely changed the understory by suppressing fire, meaning the succession of the forest is totally different now. Also many non-native invasive plants, that aren’t fire adapted, are thriving and blocking sunlight to native seedlings. The lack of fire has also made the tick problem worse.

BTW I should mention, when the forest burns often (once every 6-10 years), then you get “good” fires. Fires which are less than a meter tall and quickly move through the leaf litter and scrub layer. Trees are left intact, nutrients are recycled into the soil, new growth of fire-adapted species returns quickly.

If you don’t get frequent fires all that stuff builds up, and in fifty years you get a total conflagration that climbs into the overstory and creates a raging inferno. This is what you see on the news. These are bad and can completely destroy a forest for decades or even centuries.