They talked about that at Yosemite as well. Before they were driven out, the Ahwahnechee would periodically start fires that cleared out the undergrowth and made the valley much more open.

Here's a drawing from 1855 of Yosemite Valley from Inspiration Point by Thomas A. Ayres: https://www.nps.gov/parkhistory/online_books/hampton/images/...

And here's one from Inspation Point in 2013 : https://upload.wikimedia.org/wikipedia/commons/f/fc/Yosemite...

The forest has become very dense which makes fires larger, more intense, and incredibly difficult to control. It also makes the forest more susceptible to pine beetle outbreaks (they spread faster when the trees are close), and that makes fires even more likely.