We know how to come up with better alternatives, but as Marx also pointed out, the capitalists won't sit back and idly watch their world crumble. So putting anything else into practice is effectively impossible.
About the only time all the pieces fell into place to even begin to see anything else was Revolutionary Catalonia. However, the USSR quickly waged war with it to ensure its demise, and within no more than a few years it was no more. The capitalists who seized all the capital in the USSR under the guise of pretending to move away capitalism didn't want the people to realize that the USSR was still under capitalism all the same. That would threaten the capitalists who controlled the capital.
About the only time all the pieces fell into place to even begin to see anything else was Revolutionary Catalonia. However, the USSR quickly waged war with it to ensure its demise, and within no more than a few years it was no more. The capitalists who seized all the capital in the USSR under the guise of pretending to move away capitalism didn't want the people to realize that the USSR was still under capitalism all the same. That would threaten the capitalists who controlled the capital.