The quote by Dan Wertheimer you reproduce has struck me as being
very premature. We certainly have not explored all the galaxies or
even a fraction of them in any sort of detail that would seriously
determine if there are advanced civilizations in them.

Would we even recognize their signs if such societies did exist?
And how many professional astronomers would risk their careers
by making such a claim at this point in time?

We know of almost 300 exoplanets in our galaxy and in nearly all
cases we barely know anything about these worlds, which are much
closer than any galaxy, let alone whether they have any kind of life
upon them or not. We still don't even know of any microbial life in
our own solar system, where most worlds have had a few briefs
scans from a flyby probe at best, if at all.