For what it's worth in the article he brings up Soviet atrocities as well. No place on the political spectrum has the monopoly on being righteous, nor committing terrible crimes.
Capitalism has its roots in the idea that only those who produce get resources. If you are unable/unwilling, you do not deserve anything. And that anything includes: a home, food, water, bathroom, medicine, surgery, dentistry, or all the other essentials needed to live.
Along with that, our unique US capitalism also allows for slavery when charged with a crime. We call the Russian and Chinese detention centers "gulags" - we have enshrined their usage in our Constitution.
Mao and Stalin killed X millions. I'll accept that without research. How many people has the US killed with lack of health care? How many union strikers were murdered by the National Guard? How many African Americans were killed under lynching and 'police discretion'? How many people were killed because they didn't make enough money to matter? How many communities were poisoned with lead and other environmental pollutants because their community was impoverished?
In the end, Capitalists can crow one solid phrase to absolve their 'sins'. And that is,
"They brought their suffering and death upon themselves by not choosing better".
Am I advocating communism or socialism? No. They have been shown to not work in the previous incarnations around the world. Capitalism works, until people slip through the cracks... And those cracks day by day get ever so larger. I don't know the name of the thing I think of. Maybe its a mashup between socialism and capitalism, so that we all grow together, and that nobody is left behind.
Statist hard left ideologies (such as Stalinism, or Maoism, or even late Soviet socialism), on the other hand, have an ideological dogma that suppressing dissent by violence, even extreme violence, is perfectly okay, and even a revolutionary duty - the ends justify the means.
There are other political ideologies that incorporate capitalism (or parts of it) as an economic program, but pile other stuff on top of that to justify violent oppression of the opposition - like most right-wing dictatorships - and those would be legitimate targets for comparison with Stalinism etc. But people dying from lack of healthcare in US are not "victims of capitalism". They're victims of a specific oligopoly, that other capitalist countries don't even have.
You can claim that "it's not violence" but it is. I won't put words in your mouth, but I imagine the first thought you might have is "well, I wouldn't call that violence because imprisoning a person against their wishes for murdering another is justified." Well, in authoritarian left ideologies, beheading the ruling class was justified because they oppressed the working class, so for them, it is justified within their systems logic.
Finally, in addition to those who are expressly the target of violence under capitalism there are people who by the final result of the ideology, become victims of violence, such as those in prison working extremely low wages as the other poster pointed at. You can claim "it isn't the intent" but that argument is very similar to the argument that the intent of pre-Stalin revolutionary Russia wasn't the statist regime that it became. "It's not actual capitalism" is akin to "it's not actual socialism" which is an argument leftists make today.
And of the things that you have listed, the only one that is fundamental to capitalism is protection of property rights. And it has a direct equivalent in statist socialism - enforcement of the lack of property rights and prohibition of "economic exploitation" (e.g. when USSR banned most private trade, even between consenting parties, as "speculation", and banned hiring other people as workers). I would dare say that the latter is at least as violent as the former - but then on top of that you have to add all the stuff about violently suppressing political opposition, which is not an ideological requirement of capitalism.
> that argument is very similar to the argument that the intent of pre-Stalin revolutionary Russia wasn't the statist regime that it became
That argument is trivially refuted by looking at the arrangements in pre-Stalin revolutionary Russia, though. For example, the first Soviet constitution that explicitly drew the voting districts such that cities (where workers live) got 5x votes of rural areas (where peasants live) per capita, and anyone deemed bourgeois had no right to vote at all. That's "dictatorship of the proletariat" in action, right there.
But the other thing about that argument is that to be convincing, it requires counter-examples. And that's something that's severely lacking - we can talk about how statist socialism can be democratic and non-authoritarian in principle, but somehow none of the socialist nations that lasted for any noticeable amount of time were. This strongly implies that there's something about the ideology itself that, if not embracing authoritarianism explicitly, encourages it in practice.
With capitalism, OTOH, you get plenty of really nasty examples, but you also get examples of working democracy, rule of law, social welfare etc. Which implies that capitalism is not inherently opposed to any of those things as a matter of ideology.
But ultimately, the reason is simple: capitalism is strictly an economic system, while socialism is a economic and political system. Different strains of socialism have different political prescriptions - from totalitarianism to anarchism - but they all have some. Capitalism has none - you have to fill the missing pieces in from elsewhere (again, with a very broad spectrum, from humanism to fascism) to make a complete picture. And when you assign blame in the resulting picture, it's important to understand which of those bits contributed to it - and in many cases, it's not the economics.