"Yet so consistently did these movements fail, from anarchists to Leninist derivatives to even the democratic socialist experiments in Chile, being crushed by fascists or succumbing to capital, that it may be necessary to reassess the theory altogether."

They just didn't work because they were contrary to humans' self-interested nature. It was all based on state coercion to make people fit a theory. They weren't providing a better standard of living or more freedom, and in fact the contrary was true. It wasn't even fair because the nomenklatura lived better than the "workers". The USSR and its colonies behing the Iron Curtain just totally caved on communism because capital had plenty of food, a car, and you could buy a U2 album in a store. You also didn't have to worry about who the government snitches were.

No one made up capitalism, it has only been described. It is the natural way that people conduct economic activiry. No other system can survive as long as capitalism exists anywhere, unless the people of the collectivist country are basically slaves who can't leave to go there. Communism is essentially a prison in practice. You need the Berlin Wall or DMZ in Korea to make it work.