I have asked that question many times [1] when confronted with this type of
muhhh capitalism remark and have yet to receive a valid response. I suspect it is the result of the ideological lopsided makeup of educational institutions which churn out the message that
capitalism bad, ${my_ideology} good where
${my_ideology} tends to stand for one on the left side of the political spectrum. This does not provide students with the means to actually defend their position, only with the
correct slogans to use - a rather shallow base for a political conviction.
Of course HN is not the place to discuss politics so in some way it is probably for the best that these questions remain unanswered. It would be better still for those muhhh capitalism - and for that matter muhhh whatever-ism - remarks to remain unwritten since they are not supposed to be discussed here anyway.
[1] e.g. https://news.ycombinator.com/item?id=39866101