A trivially obvious observation from the old kraut, one that nevertheless seems to escape most people:
...the aspects of the events to be accounted for about which we can get quantitative data are necessarily limited and may not include the important ones.
It's not just that commissars of whatever variety haven't the capacity to a) absorb the data, or b) process it usefully; they cannot, in principle, even get their hands on enough of it to fail properly at a) and b).
Memo to John Maynard Keynes:
Oh, and more on Keynes via Oliver Kamm (whence I got the Hayek talk above; hey, I thought Kamm was a "man of the left" or something?):
Keynes essentially thought that if he and other old Etonians were put in charge, everything would be fine.