I think the "even when achieved is under constant attack" is key here. It means we're constantly having to treat the capitalist component as an adversary, fighting it, trying to keep it under control.
And that begs the question, why are we keeping it around at all? What unique thing is it giving us that is not achievable through some other mechanism that *isn't* a constant adversary? What is the capitalism component still doing in there to begin with?
This is all the more pressing of a question considering that essentially zero of the claims about how capitalism is supposed to benefit society (think 'trickle-down economics' and the like), have held up to scrutiny.
