Here's a geeky science analogy that can be related to ordinary life: When you vary the magnetic field around an iron bar, the magnetivity of the bar changes, however, if you try to return to the initial conditions, you find that you can't. The bar has a "memory" (this is called "hysteresis" in physics). It "remembers" the history of the magnetic field it's been in, and doesn't return to exactly its previous state.
The world is replete with examples of "hysteresis." Human affairs have it: humans, afterall, literally have memories. You cannot as a rule revert back to another condition you prefer to the present just by altering a few external variables.
This forms a basic problem with any kind of theoretical speculation based on the past. Some idealists would like us to believe that "socialism" or "anarchism" is possible, based on some supposedly idyllic moment in the history of this or that time or place or group of people. The truth is, no imagined previous state can ever be reproduced without being "contaminated" by the "hysteresis" effect of history. People can't really "unknow" anything once they've learned it. They can try to forget, and sometimes they can be made to forget by the use of force, authoritarianism, and censorship. But, of course, no authentic expression of autonomy or spontaneous, positive human development could ever come out of that.
Any authentic, durable human development is spontaneous and autonomous. That means it will always vary wildly and unpredictably from any theories we might wish to formulate about it in advance, especially about how to "improve" it. This makes any vision of utopia literally impossible. This isn't to condemn utopian visions in and of themselves, but only to chasten us about mistaking these visions for plans and blueprints. A vision can inspire the visionary to positive actions, but it can also inspire the fanatic and dogmatist to senseless cruelty and violence.