TenForward: Where Every Vulcan Knows Your Name

A good counter example is vaccination.

Let's say a benevolent alien ship passes by, and discovers a planet with a 90% child mortality rate, due to disease. They introduce vaccines to the population which drop it to under 10%. That's great.

They return a few decades later, and the civilization is in shambles. It turned out that birth rates didn't change much. The population started doubling every 5 years. Food production couldn't keep up. The subsequent wars famine and civil unrest devastated the society.

We've seen similar problems, to a lesser extent, on earth. Providing cheap, second hand cloths to Africa ended up destroying the local textile industry. Many places are now dependent on that aid.

In star trek, Star fleet seems to do fly by visits to many places. They are not equipped to assess the results of interference. That would require a team onsite for long term study and assistance. You would need to improve multiple areas at once, each supporting the others. We see some evidence of this, in some episodes, though it is lacking.

The pre-warp limit also makes some sense. It's an obvious marker for a society. By that point they have likely learnt the lessons with neive help internally. They can assess the risks, and introduce them carefully. They are also likely close enough in technology that the boost won't destabilise their economy etc.

It's far from perfect, but as a rule for fly by captains, it makes a good amount of sense.