Earlier quoted context omitted.
I think the centre of the point of contention (and we can work outward from there) can be isolated like so: have there been zero authoritative personnel that have claimed or implied that fraud sufficient to change the outcome of an election is impossible? And while contemplating this idea, remember that we are dealing with human beings.
Nothing is impossible. But the chance of the being sufficient fraud to change say the presidential election is extremely unlikely, especially given the evidence that we have.
Technically, this isn't true.
> But the chance of the being sufficient fraud to change say the presidential election is extremely unlikely....
Technically, the likelihood is not known. Humans are welcome to state estimates of the likelihood, and believe those estimates to be true (and rebroadcast them, seeding the "fact" into other minds), but base reality is where the truth lies. We can (and do!) pretend that our estimated reality is factual but this is a collective cultural delusion, and a harmful one at that (which sometimes people can see clearly (in the behavior of our outgroups), and other times not (in their own and ingroup behavior)). Pick any culture war topic thread on HN, and observe how people describe "reality" - the phenomenon is not really hiding as much as we aren't able to see it (similar to how we couldn't see certain things until we developed techniques, like using lenses to see into different realms of reality).
> ...especially given the evidence that we have.
Our discovery of evidence has no influence on that which preceded it, it only has influence on our beliefs of that which preceded it. Unfortunately, we often tend to not form a distinction between the two.