I don’t think capitalism is to blame in this particular instance.

As I recall, Britain arranged the Acts of Union so they could exploit Ireland as a cheap source of food, labor, and soldiers. The success of the Napoleonic Wars encouraged them to accelerate production by any means necessary. They may not have intended for Ireland to become a food monoculture, or anticipated its failure by 1840, but they certainly did little to remedy the situation their imperialism brought about.

Why did Ireland export food while the people were starving? Capitalism. The poor tenant farmers had to export food to… pay rent!