They Really Believe This
The explains the persistent belief in folk economics.
Mentally, I'd like you to replace "capital" with "big piles of money" wherever you see it. That's a gross simplification but I think it also makes some things more clear.
An economic system is one that determines a) what goods/services should be produced and b) how to distribute them.
Capitalism supposes that a) and b) ought to be determined by (people with) Big Piles of Money
It's "big piles of money-ism".
On the other hand, the phrase “big piles of the results of the voluntary decisions by consumers-ism” sounds awkward.