Well, it doesn't even have to be as extreme as Blink of an Eye. Simply contacting new species, whether warp capable or aware of the interstellar community or not, alters/influences them. Any interaction with people at all is a form of interference. If you were truly non-interfering, you'd be isolationists. Heck, there's a point to be made that even just observation can potentially have affect. So own it a little bit, & avoid or mitigate the negative effects wherever possible or necessary imhoThere was that one episode on Voyager...Blink of an Eye, I think? Anyhow, because of a different temporal point of reference, the starship Voyager ended up influencing the development of a species simply by remaining in their planet's orbit for hundreds of years.
In any case, I've noticed something in the aggregate: if someone wants to take a dump on Star Trek and its Prime Directive, this is always a "no win" scenario for The Federation. If The Federation neglects to interfere in the affairs of pre-warp civilizations, they are callous and holier-than-thou. Alternatively, if the Federation deliberately interferes in the affairs of pre-war civilizations, they are (indirectly?) enforcing conformity through homogenous technological (and therefore cultural) development; critics will occasionally reference that naked right-wing mouthpiece on DS9, Michael Eddington (he compared The Federation to the Borg...silly, right?).
The hard directive itself seems to only serve dramatic device, when we need to say "ordinarily we wouldn't be getting involved in this, but..." It's a way to add weight to a scenario, by implying taboo to their actions.