Any discussion of the shortcomings of Socialism takes about 3 statements to devolve into the hoary whine that "real Socialism" has never been tried, always because "the right people" are never put in charge. This is then extended to argue that "real capitalism" also has never been tried because when it has, it quickly results in something like an oligopoly with a handful of the very rich oppressing the remaining 99% of the population.
The best example of this was the Russian nationalization of agriculture in the early 30's (I think). Instead of hundreds of farmers jointly providing food for a large part of the world, they got 60-odd years of "bad weather" with instead of many well-to-do farmers, they got one VERY well-to-do
If you ask what Socialism is, you get a word salad about a happy and prosperous land in which no one is wanting, and recommendations to read a large stack of thick books starting with Das Kapital. Ask what Capitalism is, and the left will describe a system that works much like the old Soviet Union, only with results that almost exactly mirror that system.
Let me try to simplify: Capitalism is trade with some rules to keep people honest. That's about it. Socialism is absolute rule of law with trade being incidental to the rules. No matter what, some government intervention is necessary, on one end to prevent actions that impede trade, and on the other, permitting some trade to keep the peasants from either revolting or simply starving to death.
Here's a simple graph: