This was not supposed to happen. None other than The U.S. Federal Reserve Bank of Dallas, in a research paper released in January, said that

A drop in oil prices brought about by rising supply — like the current one — should boost global growth by up to 0.4 percentage points. “This is mainly due to an increase in spending by oil-importing countries, which exceeds the decline in expenditure by oil exporters,” the paper said.

And of course, as Bloomberg reports, there is book-talker and status-quo-maintainer BlackRock Inc. Chief Executive Officer Laurence D. Fink.

“The reality is 4 billion human beings are going to have cheaper energy, cheaper heating, they’re going to have more disposable income,” Fink said last month. “And ultimately that’s going to re-accelerate the global economy. It may take six months, it may take a year but this is all good.”

So far, though, consumers in developed countries aren’t behaving as they should: spending the windfall from cheaper energy. This time around, “the pickup in consumption in oil importers has so far been somewhat weaker than evidence from past episodes of oil price declines would have suggested,” the IMF said in January.

The reason: cash-strapped consumers are using the savings to repay debts.

Furthermore, as Bloomberg reports, low oil prices have prompted companies to cancel dozens of capital-intensive projects — like drilling wells — which in turn means lower demand for machinery. Wood Mackenzie Ltd., an industry consultant, estimates that at least $380 billion has been put on hold. IHS Inc. puts it at as much as $1.5 trillion.

Whatever the amount, the IMF says the impact on investment in oil and gas new projects is “subtracting from global aggregate demand.”

So with economists desperately clinging to their textbooks – where for the last 75 years, almost every economic crisis has been preceded by an oil price spike, the worry now is that low energy prices are pushing the global economy into a tailspin.