The question I invite you to explore is whether or not NFs truly have fulfilled their causes. Or in other words, are their endeavors truly worthwhile?
First of all we should define the matter of the situation as clearly as possible.
What kind of causes do NFs tend to fight for? In literature they are portrayed as fighters for the happiness of society, the common good, and the welfare of the individual.
Some examples of those would certainly be Buddha, Jesus and Ghandi.
We know for sure that this is what the NFs are portrayed as fighters of. But was this really the case?
In order to truly know this we must psychologize those heroes to see what they were thinking.
A first step to this would be attempting to discover how an NF's mind works, granted of course that the NF is a pure type.
They are first and foremost concerned with collecting abstract perceptions of the environment and then making value judgments about those perceptions.
Both of these are amorphous, as few would find it hard to agree that Feeling is not nearly as neatly organized as thinking. It is moosh.
Intuition is simply pure abstract perception. From this it seems we are in the position to adduce that the NFs are unlikely to have a clear view of the causes they were fighting for.
To answer the earlier question, were the causes they truly stood for as magnanimous as we think they were. We do not know. Neither do they. Unless of course those NFs were exceptionally gifted at the use of their inferior or tertiary Thinking faculty, which is highly doubtful.
What else do we know about Feeling? That it tends to dramatize? Prone to wishful thinking? It seems far more likely that the causes appear magnanimous because NFs and their followers have romanticized them.
The truth is they were confused individuals driven by blind and amorphous forces of passion who made such great noise of their endeavors because they sought approbation from others. Much akin to a typical drama queen. All of us who operate almost exclusively on emotion will obviously seek affirmation for our passions and will clamor at great length to receive the approval we seek. This is clearly descriptive of the NF stereotype. And certainly the heroes of history such as those listed above were very reminiscent of the NF stereotype.
In the end, no they have not fulfilled their causes because they did not know what their causes were. Because their modus operandi and message were highly emotional and had little respect for the truth their life and quest were distorted. As a result we have many stories concerning how they fulfilled this or that romantic mission without having a clear idea of what this mission is, much of which has been fabricated altogether by their followers who eulogize them without respite. They are but prey to urban legend for us to exercise our imagination upon, their statures have degenerated into an empty vessel for us to fill in with whatever may serve our purpose. This is why we have many different sects who profess to be followers of Jesus who all have radically different views of who he was and what he taught. This has gone on until Emperor Constantine exacted pogroms of those who disagreed with his view of that man's teaching. Same could be said for Muhammad, Buddha, Ghandi or any other leader who has been purported to have shown us the path to virtue.
All worldviews founded upon emotion and not clear-cut rationale are bound to degenerate into chicanery. They will later be used as an instrument to promote a political agenda of this or that delegation. The Taliban, the Ku Klux Klan, modern Christianity, are all founded on amorphous values and for political reasons insist on proselytizing to the end of convincing others to embrace their values. They are all mendacious and rapacious and I think will end up destroying civilization. All springing out of the root of NF causes.
We ought to stop trying to turn Earth into heaven, as we have only succeeded in turning it into hell. NFs ought to stop acting out on their Feelings, no matter how strongly they feel they are doing a good thing. Not only will the vision likely be confusing and inapplicable to the real world, but also being driven by emotion will also lead to a confusing mindset. As obviously emotions do not give us a clear perspective, one distinct example of this is the aforementioned need for approbation such a mindset leads to. This alone suggests that such a hero was driven by unworthy motives. Thirdly, this opens the door for charlatans to take advantage of the cause in any way they see fit.
If we truly have serious intentions about making the world a better place we ought to stop and think, organize our mindset into something coherent and then see how this could be implemented to the external world. It should be founded upon a clear-cut rationale concerning making the world a better place, not torrential passions.