The commenter who identified that we’re now able to eliminate radiowave-broadcast communications, via lasers ( & fiberoptics, etc ), is spot-on.
There is another angle, though.
Imagine a simplified-model of civilization…
a batch of 7 newborn-babies, instead of hundreds of genetically-distinct populations in Africa…
those 7 babies live in “eden”.
they learn that they can consume everything they want, that doesn’t harm them.
they learn that they have to be somewhat self-moderating, because others fight them when one crowds the other, too much.
etc.
they move away from each-other, & some lose their skin-pigment, others change it…
an empire forms, in-which industry is the rule ( the Roman empire ).
Now a momentum is set in-place, that is making the sequence of the Industrial-Revolutions inevitable…
at the time of the Roman Empire, the children are, say, 11yo.
at the time of the Industrial Revolutions, they are in puberty, their brains forced into chaos, & ALL sorts of new force-multiplying technologies landing in their hands…
So, what is The Great Filter?
What happens when it is unconscious-toddler-mind, or unconscious-adolescent-who-never-got-challenged, who has all the world-snuffing technologies that we now have, but who has the global-responsiblity-level of … drunk & drugged narcissistic children…
Say you have 7 kids going into The Great Filter, representing the whole populations-sea of our world…
Say only 1 of them survives The Great Filter…
Are they going to be CAREFUL in what they do, technologically, from then on??
Obviously.
I don’t expect more than about 1.5% of this planet’s population to survive this century’s TANTRUM/POGROM that has narcissism-roots, politics-roots, religion-roots, food-insecurity-roots ( like total collapse of the terrestrial & marine food-webs, later this century ), etc.
Will the remnant who survive this century, if any do, be as careless with technology as we currently are??
How could they be?
If The Great Filter is an automatic force-growing-up consequence of EVERY world-overwhelming-species, who mixes accommodated-immaturity with ecosphere-destroying technology, then whatever portion of worlds who reach The Great Filter have survivors of it, … it’d be inherent in the survivors’ experience that they have been made careful.
Same as you don’t find incapable-of-self-discipline in career-military-officers, you don’t find our murderous carelessness/ideological-rabies in any survivor of The Great Filter:
Universe automatically force-extinguishes populations who won’t grow up, who gain the technological-leverage that we’ve gained.
So, silence depicts a lack-of-carelessness AND an absence-of-need to be throwing-away-energy through radiowave broadcast, both.
When combined, galactic silence makes much fundamental sense.
We’re in our species’ “puberty” stage, and haven’t survived our force-growing-up Great Filter, yet.
If we do, well, then finding others who also did, will make sense.
If we won’t, … then our epitaph will be that we wouldn’t grow-up, at ANY cost.