Benefits from the longer term increase in the dollar gold price have been whittled away by rising capital expenditure costs, at existing operations (stay-in-business capital expenditure), and at new mines, where build decisions have sometimes been based on mineral economic feasibility studies that no longer look so robust. Costs have a nasty habit of rising, and then not receding to previous levels, and then rising again.
I made a similar point earlier in "Where's The Leverage?", but my hunch on the source of the cost pressure was wrong. As Segeant said, ballooning capital costs are to blame.