Earth has a conveniently oxidizing atmosphere in which hydrocarbons burn easily, but not so oxidizing that it prevents stable carbon-based life. Quite a narrow window, really.
The limiting oxygen concentration for most woods is between 14% and 18%. The Earth oxygen concentration is a little over 20% so it does look close. But this is slightly misleading: All that oxygen showed up because carbon based life was releasing it from water and carbon dioxide in photosynthesis. Oxygen using life only showed up after there were dangerously high levels of oxygen. And if the oxygen levels get very high then the photosynthesizers will start to get poisoned and the percentage will go down. So it isn’t really likely to have an atmosphere with so much oxygen that it is a problem for carbon life.
But yes, certainly an equilibrium with less oxygen is plausible in which case fire would be close to impossible even if the percentage dropped by only a small amount.
The limiting oxygen concentration for most woods is between 14% and 18%. The Earth oxygen concentration is a little over 20% so it does look close. But this is slightly misleading: All that oxygen showed up because carbon based life was releasing it from water and carbon dioxide in photosynthesis. Oxygen using life only showed up after there were dangerously high levels of oxygen. And if the oxygen levels get very high then the photosynthesizers will start to get poisoned and the percentage will go down. So it isn’t really likely to have an atmosphere with so much oxygen that it is a problem for carbon life.
But yes, certainly an equilibrium with less oxygen is plausible in which case fire would be close to impossible even if the percentage dropped by only a small amount.