I'll go along with what Holdfast wrote. Its ultimate purpose is to protect The Federation from the pitfalls & repercussions of having to take responsibility for everything you come across throughout the galaxy, with the added humility of suggesting that they themselves could also be a potentially corrupting influence on cultures of lesser development
Starfleet Motto: Always assume the worst. Better to die than let them see you, and better to let them all die than continue living.
Best way of saying it.
And with my own Dr. Who/Trek crossover, I'm getting this image if Defiant and Sovereigns chasing a tiny blue polic box in space, weapons fire showing near it, and throughout every Federation planet, there's the equivalent of a wanted poster with Tom Baker's face on it, with "Starfleet Enemy Number 1!" below.