Exactly. A hybrid passenger car can tolerate unpredictable power output that may come with an auxiliary power setup that may or may not be available when stronger dynamics are called for.

A plane doesn’t have this luxury and needs predictable output. The fossil fuel engine either needs a sacrificial “overboost” mode for emergencies (at the cost of wear/long-term longevity), or has to be sized for full power at the ultimate cost of efficiency.