We are the only intelligent more-or-less spacefaring species that we are aware of and if we can't do it why would we think other hypothetical intelligent spacefaring species can do it.
Are you just questioning the Von Neumann machine aspect or the entire feasibility of sending a basic dumb probe out to another star for a fly-by?
Not necessarily. I think you underestimate how much of space is space and how little of it is anything else... and that most of that "anything else" is dark matter. Only ~4% of the mass energy of the entire universe is matter.
It seems more likely than not to me that any arbitrary path through interstellar space would never pass near anything larger than a grain of dust.
https://wiki.evageeks.org/First_Ancestral_Race
(Though I suppose two probes would have to accidentally land on the same planet to lead to that outcome.)
Part of the Fermi paradox they skipped in this article is the idea of a Great Filter which prevents life from evolving or creating a space faring culture. The assumption is that we're past the filtering event, but it's entirely possible that we haven't reached it and in some unknown future our race will cease to exist.
Imagine a technology which would allow a single insane being to destroy the entire planet, or at least all intelligent life. We're not too far off from that point now if you consider modern political power. If that point of technological advancement is inevitably discovered prior to the technology required to become a space-faring race.
The idea of an individual or small team of scientists creating a world-threatening virus or triggering nuclear war is not that far outside our current state of affairs. Interstellar space travel is likely at least 100 years in the future.