Jim, but a rational person would naturally ask why those targets were "paper targets" - unless of course we want to give credibility to bourgeois ideology of 'irrationality" of non-market systems.
As I argued elsewhere, central planning can be theoretically defended as creating superior to market rationality by slashing down transaction costs resulting from imperfect information. However, in order to work in that capacity, planning must create an efficient mechanism for information flow to set forth optimal production targets.
It is a well documented fact, however, that such information flow was less than perfect, to say the least. In plain Englsih, SOE managers fed misleading information about their true productive capacities, resources etc. to the central planning authorities. Knowing that, the planning authorities implemented the practice known as "taut planning" or imposing production quota that assumed higher than reported productive capacities. Since the planning authorities had no way of knowing which SOEs uinderestimated their reported capacities and by how much, the whole process of "taut planning" was reduced to a guessing game. Hence overproduction of certain items and underproduction of others, as well as the proliferation of informal barter between SOEs to make up for the losses, inefficiencies etc. - which further exacerbated the SOE's management need for underreporting (they could turn the 'hoarded' capacities or goods to profitable barter).
So the real question is why the information exchange system was less efficient than planned - which leads us in the direction of examining institutional ramification of knowledge producers. It is my contention that it is the latter-days "boyarschina" or factory managers and intellectuals who finished off efficient planning in the pursit of their own class power. This also explains why 'bat'ushka' (uncle) Stalin was so paranoid in his distrust of these ratfuckers. Of course, that explanation will not play well in the halls of harvard, yale, or chicago.