The problem is that 'everyone is the hero in their own story'. Everyone who spreads falsehoods in service to some cause is convinced that they are doing the right thing and are trying to "bring about a good thing".
Is there any advantage in winning the war if by doing so you lose your soul?
This is - of course - a very rough synopsis of Machiavelli's treatise - even if he never actually said that.
But the other way of looking at his work was that he was the first person to develop a code of ethics that led to the idea of "doing the greatest good to the greatest number of people"
I highly recommend the series from the blog of the this Renaicance scholar and specialist in Machiavelli which I discovered via HN the other day: https://www.exurbe.com/machiavelli-s-p-q-f/
He argues quite compellingly that Machiavelli's work led to classical utilitarianism ethics ("the greatest good to the greatest number of people") since he was the first to consider judging actions on their consequences rather than "what was in someone's heart".
Determining this, even with the information available today, seems like folly; like a never ending circle of statistical manipulations and justifications to support preconceived notions.
Action on just about any social issue of note can be argued one way or another to be satisfying this guideline.
It would be worse for central planning, because in addition to the problem you mention, central planning has the problem of getting the necessary information to the central planner, which in the general case is impossible: the information goes up as the exponential of the population size, but the bandwidth of information channels to the central planner only goes up linearly with the population size.
Does that mean you can't actually know what the greatest good is? We can probably get very close to knowing it, and the little details shouldn't matter. But most of our "social issues" are squabbles over these details, and the good never gets done, or becomes reduced.
For all the popularity of the phrase "the end never justifies the means", I have never met someone who actually believes it. Just to begin with, almost everyone agrees with state sanctioned violence as means to maintain a social order, even if they find the action itself horrible.
I found the phrase itself more commonly used as a way to dismiss certain ends on the grounds of PC than an actual moral objection.
I've definitely met people who agree that choice and liberty is so important that it's better people lead shorter, less healthy and more miserable lives through their own choices, than be tricked or forced into prosperity, health and happiness.
Each it's own ideals, but as mentioned, I believe the phrase is just used to quickly dismiss ends that people are if not against, not so invested in.