First, the economics.
The most important feature of an economic system is who makes the decisions. That choice can and should be made with respect to every good and service, but efficiency demands that there be a default assumption. Under capitalism, the economic decisions are made by private entrepreneurs, with such exceptions as the voters demand. Under Marxism, such decisions are made by the government, without exception. Private is better, not only because the chance for profit attracts investors, but, crucially, because the fear of loss constrains them.
Loss keeps the profit-seeking engine on the tracks. Imagine you’re a venture capitalist and some kid with a bright idea says “If my idea works, you’ll make a fortune, but if it doesn’t, a Genie will give you your money back.” In that world, kids with bright ideas would be coming out of the woodwork, all touting something great with no risk of loss. The competition would create some basis for choosing among ideas, but the risk/reward ratios would be skewed from real-world conditions. Way too many bad ideas would be dreamed up, written down, and listened to, all of which is a great resource suck, and all of the benefits of loss-avoidance would be lost.