It's more than that. Not solve your problems, survive your problems.
"Oh your planet is a shit hole and you're about to die from nuclear warfare? Everyone where you are at are murdering everyone else? Well... sucks to be you, prime directive bitch. If we help weak, immature civilizations survive they'll make a mess out of things at an interstellar scale, civilizations need to live or die on their own"
Data literally mentions letting the weak die in the first season of TNG. Unfortunately part of the shift in TNG to get away from the goofy TOS feel also meant stripping away a lot of the focus on scifi cultures, philosophy, worldviews, in favor of focusing on characters instead. Which... fair's fair that was completely understandable. Rodenberry was great and his vision was great but he was also really weird and so were his ideas. First season TNG has far to much of TOS in it.
But yeah, original federation was very much into the whole 'being kind is not nice'. Among their moral principles they valued a pretty good amount of ruthlessness.