It is also a matter of fact that the ruling economic theory does not correctly describe reality. Indeed most of it does not even make an attempt. The primary contribution of academic economists is the repeated attempt to prevent/explain/explain away the business cycle. If you keep score as you go through life, you'll see how well they've been doing.
No. Kalecki and Keynes basically founded macroeconomics in the thirties and while there has always been an ideological battle between Keynesian and classical economics the syntheses that resulted from the clash of these two schools are not at all denying the business cycle. This
is contemporary macro and if you just read the abstract you will realize that it actually does deal with demand management problems. There is no business cycle denial as business cycle is the very research topic!
There is a difference between academic research and the popularization of it. When Bob Lucas or John Cochrane or some other right-wing asshole from around Chicago denies that one can do something about recessions it is propaganda and not academic research.