Leftists manage to be brilliant by not being brilliant. They disregard the long term and act toward pettiness in the short term, effectively managing to sabotage any attempts to rise above the lowest common denominator.
They drag down others by making good behavior expensive, in other words. You found a way to irrigate your village? You are a witch doctor, and must burn. You became successful at your farm or business? You are the enemy, “the rich,” and now you must pay.
Once they took this to a policy level, society became hopeless because each new Leftist policy set precedent, and all of these tied our hands. You have to work around the red tape and other stumbling blocks, which just makes the Left more powerful through the art of strategic compromise.
This resembles what we know call mosaic warfare, or defeating your enemy by obstructing any possible decisions, leaving them with nothing to do but consume themselves:
Instead of attempting to destroy an adversary’s forces until it can no longer fight or succeed, a decision-centric approach to warfare would impose multiple dilemmas on an enemy to prevent it from achieving its objectives.
In other words, the more problems you create that someone else has to fix, the more you block their potential methods and goals. If you spam them with little crises, they spend all their time putting out fires and in doing so, ignore you and affirm you as part of their relationship with other parties.
The Left won by not having a big strategy, only a passive-aggressive one. The more they sabotaged, the more the Establishment at the time went from being leaders to being janitors. That enabled the Left to criticize the janitorial standards.
In the West, we have spent the past couple of centuries fighting over problems created by Leftism, with Leftists pushing for more Leftism as a solution. It almost appears that they know their policies do not work, and want them to fail, so that the system fails with them.