Except lots of cancers now have cures, and there are vaccines for others, so no it isn’t.
Yes, and there have been successful Socialist revolutions, you’re only weakening your point.
Do you believe the remaining cancers will never be cured because they currently aren’t?
Successful ones? Which country is currently a socialist one? Where do the workers control the means of production?
The PRC, Vietnam, Laos, Cuba, and a few others are currently Socialist and run along Marxist lines.