[mjan22640]

The benefit of mitochondria is in the isolation of the high power reactions, that involve chemically aggressive elements, from the rest of the cell. That allows for high energy throughput without self damage. Cells that do not have mitochondria run the same or analogous power producing reactions, but at a much lower volume, to keep the damage sustainable. An alternative option to mitochondria would be to evolve some means for isolation of the power production.