@MagpulPony
It would actually, either through how far away said craft’s base is
(i.e. the further away, the more shielding and/or point-defence needed to safely get here to study us), the general tech needed just to get here
(if you can build a craft to get here, the defence mechanisms will be far more sophisticated than we can even imagine), or just the general common-sense that would come with the former two that should point out that visiting possibly hostile primitive aliens should mean taking precautions around them. Remember that they aren’t coming unprepared, as the presence of CFCs and methane in our atmosphere, not to mention radioactive particulates from nuclear testing, would give away the tech level of the aliens they’ll be observing, thus don’t really have any excuse for being vulnerable to said aliens primitive chemical-driven weapons.
I’m not saying it’s an impossible event for humans to have shot down an alien craft, but that it would be extremely improbable…on top of the extreme improbability of aliens visiting us…on top of the extreme improbability of aliens evolving near us without us noticing…on top of the
49 or so other factors in the Fermi paradox that states that advanced alien civilisations are improbable.
Don’t get me wrong, it’s fun to speculate, and
Destroy all Humans! is one of my favourite games involving the subject of alien visitations. I just consider it extremely unlikely given the physical constraints and how young the universe is for such things to happen.