capitalism refers to a system where socioeconomic power is primarily concentrated in the hands of a capitalist class
No. Capitalism is a system where socioeconomic power can be sold and bought in the form of "capital". It's true that this inevitably leads to a concentration of power, as those with lots of capital can easily get the means to buy more capital while those with less capital need to slowly sell the little they have just to scrape by, but skipping that part and just saying "capitalism is about being evil" is unhelpful because then people will say "we'll, I'm not advocating for just being evil for evil's sake, I'm advocating for allowing free trade of capital"