Capitalism is amoral in and of itself. Capitalism coupled with social darwinism can lead to some pretty bleak outcomes. For example cutting off kids genetalia for $$$$.

Now it doesn't really matter if most people find it ghastly and horrid, all that really matters is that someone who doesn't find it ghastly and horrid will do it for $$$ and seeing as they are making the $$$$ other people will copy them, and they'll have monetary incentive to go against the person who is trying to oppose them using the full power of the state that the $$$$ provides.

Free markets and basic principles of capitalism tend to be quite good. But unlimited unrestricted capitalism, or better describes as profits motives leaking into civics is probably not a great thing. One leads to corporate monopolies enforced by a government that is financed by corporate interests and controlled by them rather than by the people it's supposed to actually represent. The lines between them are of course fuzzy.

Communism has the same problems of course, money and power are essentially the same thing in the same way matter and energy are the same thing. Communist systems work differently but the very same lust for power/profits can infect the system and lead to bad ends as well.

I think the main problems come down to centralized control. On the one hand you need a kind of central power to act as a referee to keep other interests from running amuck doing whatever they want, on the other hand that central power can easily be bent to the will of a small minority of power hungry individuals rather than represent the collective will of the people.

Like read Marx you'll get some good ideas there, namely how industrialization supplanted agrarian social orders and replaced smaller less centralized communities that had been fairly well established with an entirely new kind of social order based around the accumulation of power via capital rather than feudalism. I don't think this change is entirely a bad thing, but it definitely is a root cause of a lot of social problems.

Then there's loads of bad ideas Marx has specifically with his utopian society bullshit. It's funny how naive it is. The strong will dominate the weak regardless. It's better to try to organize society so that the strong dominate the weak in a way that uplifts and protects the weak and prevents other strong people from fully exploiting them, but if you ever manage to impose some classless societal communist Anarcho whatever system why do you think it won't just degenerate right back into a kind of feudal tribalism?

I mean imagine if by some magic all property was communaly split evenly amongst everyone, and taking that initial state, what's to stop me and my friends from deciding we are stronger than everyone else, riding our horses over to the next village to steal their crops and women for ourselves? They'd have to defend themselves obviously, meaning they would need to have people who are strong enough to protect their own weak, meaning of course, they are also vulnerable to their own society being dominated by the strong.

If I'm out risking my life fighting bandits each day to protect the weak ass agrarian farmers then I like want double the food and double the women obviously. And if they don't want to give it to me I can just take it easy, or not protect them and go out freelancing as a raider myself.

That's the problem with utopian socieites, like all societies they exist on a razors edge of collapse at any time. The only way to maintain social cohesion is through the use of force of some kind, and one could easily argue that the use of financial means as a form of persuasion is far less cruel than simply using a gun.