Generally the idea is that historically there were frequent fires which kept the available fuel to a lower level.

Humans started fighting wildfires, and for decades we were pretty successful. That resulted in more fuel buildup then happened historically.

When those fire finally burn, they often burn hot enough to destroy trees that used to survive the fires.

I don’t know what the fuel levels were in this area specifically, but yes, it seems plausible that the brush might not have built up to today’s levels before.