> I'm sure the Party thought they had a good reason.
They did, and it’s one of the key reasons centrally planned economies always fail (really their resistance to failure is only determined by their people’s endurance for suffering). In a free market, value is set by supply and demand, bad decisions and bad ideas don’t survive, and you have some reasonably decent metrics to measure success. In a planned economy, value is set by the planning committee. As a decision maker in such a system, your value is determined by how successful you are at convincing those higher up the chain that you have good ideas and make good decisions. Every decision maker in the chain of command is incentivized to lie to their superiors, and the ultimate authority is incentivized to lie to the public. Small failures and course corrections are not possible under such a system, so for a failure to be acknowledged, it has to overcome the ability of the person who’s responsible for it to conceal it. It becomes essential for anybody with any power to control the “truth”.
You can see the same dynamics at play in any sufficiently large organisation (generally scaling proportional to the slowing feedback loop between decision and outcome, and with any form of complexity that would obscure the direct relationship between decision and outcome), though usually on a much smaller scale. China allows enough free market activity to take place to allow it to survive, but you can see the failures of its planning committees everywhere.