Given you mention NAACP I'm assuming your comment refers to US-based organizations.
In that respect "feminists" won a landmark victory in 1973 that was just recently overturned in Roe v Wade. That's one example of the importance of "sticking around".
As all your examples are of groups leaning one particular way politically I'll proffer another example from other side.
Consider the NRA, presumably they don't need to exist as the 2nd amendment enshrines the right in our constitution.
As you may point out that right is under constant threat. Apply that same logic to the groups you're disparaging and you may better understand their purpose.