Actually, I believe that capitalism-with-state-regulation is the only system with a prayer of working with human beings. You can have bug fixes to patch the shortcomings from theory to reality (a state to regulate natural monopolies or run public goods that no private company can provide), and you can have a certain level of income redistribution to stop inequalities from appearing and to make life a bit easier, but that's it. A no-state "total free market" world would be a nightmare in which many services wouldn't exist or would be provided in the most unfair way you can imagine, and fully-state-run systems (from communism to Chinese State Capitalism) introduce so many distortions that you end up either breaking the economy altogether or causing abject inequality.
In the end, both no-state laissez faire and communism require humans to have a generous, selfless nature real-life people do not have, because one single selfish person can break them to death, and incentives in both precisely push you towards abusing them.
I grew up in a very lefty family (my aunt works for a communist trade union, and I'm currently looking at Das Kapital in my shelves as I write this), but I can assure you that nothing works better than a system in which there's the biggest, freest competition in every field, and in which there are dozens of companies flogging the same goods, allowing consumers to choose. But since some sectors are harder to get into, and companies will try to buy the competition and consolidate, that's where you get a state to regulate it. Anything that goes out of that is not " an extreme", it's just an ideological system that may work in theory but fails when faced with real people.