There's one feature they forgot to mention in terms of SETI detection: Even working under the assumption that alien civilizations have generated signals we can

There's one feature they forgot to mention in terms of SETI detection: Even working under the assumption that alien civilizations have generated signals we can recognize as artificial, we've still got the ultimate needle-in-a-haystack problem: Any such signal will be millions of years distant from us in both time AND space. Even if an alien civilization lasts 100,000 years before collapsing, we probably won't ever receive any of their signals because our overlapping windows of capability are so small (even if we also survived 100,000 years). They'd have to be close enough to us both in terms of distance (in light years) and in time (years we've had our capability and they've had theirs). Think of it like a Venn diagram with circles the size of your fist and a workspace the size of our galaxy. Because of this, even if we're not alone in the universe, the chances of us detecting a guaranteed-to-exist alien signal is almost nonexistent, and the chances of actually meeting an alien are exponentially smaller than even that. The only way around this problem would be a civilization that seeds the universe with robots that can lie dormant for billions of years, and activate upon detection of a signal-capable species.