We are talking about the vastness of an entire GALAXY and a level of technological advancement that comes with consequences that no one can even begin to imagine let alone predict. The entirety of human science fiction doesn't even scratch the surface as to what is possible (and due to our own biases and the need to entertain a television audience/readership is probably far more tame and boring than what is really out there) at those levels.

You're talking about quantum limits but you have to realize, to make the vast majority of science fiction watchable/readable, you have to almost entirely throw out our knowledge of modern physics. For example, every real world attempt at theorizing FTL travel has lead either to needing ridiculous amounts of energy (equivalent to the mass of Jupiter for the original Alcubierre drive which would be about a billion billion billion kilograms each of matter and antimatter) or particles with properties which we have NEVER come close to seeing (and by never, I mean not a shred of experimental evidence or even a suggestion that it exists outside of a theoretical framework). If an alien race has FTL, it's knowledge of the universe is well above ours and any attempts we can make to predict the limits of their technology is useless. For all we know, FTL travel might be as difficult as building your own solar system from scratch.

In order for us to have an alien visit that is even close to any imagined encounter in science fiction, many things that we can't speculate on would have to work out. We're not talking one black swan, we're talking about an unknowable number of factors and events that would have to work out just right.

It's might be possible (we don't even know if FTL is possible), just like it might be possible for wild pigs to evolve to fly without any artificial intervention in a few thousand years, but it's so unlikely that it's worth putting into the "Just not going to happen pile," all the while working to prove yourself wrong :)