The Prime Directive solution to the Fermi Paradox

This is not an original idea, the Prime Directive solution to the Fermi Paradox can be noted as the Zoo hypothesis. I'm just emphasizing what I think is the best reason for setting the Prime Directive.

Fermi Paradox

How come we've never been contacted by aliens? The universe is so big and old, that statistically, some civilization must have already developed the ability of star-travel.

Prime Directive

Never interfere with younger civilizations (from star trek).

The best reason for setting the Prime Directive

As far as I know, any contact between an advanced civilization and a native one in human history has always been disastrous to the native civilization (see: Chronology of colonialism).

The prospected visitors to earth have probably experienced these types of contacts within their planet before achieving interstellar travel. Hence, came to the conclusion that contacting less advanced civilizations can only hurt them.

Therefore, they set a rule (a "prime directive") to never contact less advanced civilizations.