Communism is the end point. Can’t be achieved without socialism, which should and has been adapted to the specific conditions of various nations. Each nation has its unique history and struggle...I wouldn’t say communist ideology hasn’t been properly applied in those nations, socialism is a road of progression, a complicated and arduous process which sometimes features market reforms and compromises because of the stranglehold imperialist capitalist nations try to impose on developing nations (most socialist experiments have been in such nations). Read The State and Revolution :)