Wait, were do the the Romans and the Mongols stay in this picture? Were they capitalists as well?

There is an implication that Capitalism is what led England to colonize half of the world and enslave people. Logically, if the Romans and Mongols did it as well, then we can no longer attribute this to Capitalism alone.

If I read "Capitalism and it's (sic) atrocities must be understood by the people", then I'd expect to get an example of something that happens only on Capitalism. Capitalism has countless issues, but I wouldn't put "it enabled empires to do Imperialistic stuff" on this list, is all I'm saying.