That is why it is totally impossible to plan the economy. In fact, no one should be in charge of the economy and have a structural power to pick winners and losers.
But still, it remains to say that those who are for a planned economy, do it for one simple reason which is very human, which is that of having a power trip for themselves to play the central planner. Of course, the easiest thing to do for any lobby is to »buy » the central planner.
Of course, the less to »buy », the better.