I think the peak has been reached already. It's either:
Capture/uplift a species only to genemod them to being delicious and turn them into livestock, or make them into slaves and sell them back to their own empire.
I still think the peak would've been a Bioreactor thing I saw mentioned. It doesn't work NOW since Matter Converters don't exist and Bioreactors only for machines, but the idea was take a species, Livestock Slavery/Processing Purge them for food, put that food in a Bioreactor for energy, put that energy into a Matter Converter for minerals, process those minerals into alloys, and then make ships out of that species to fight their empire.
One day. One day.