On the more general question of whether intelligent life would arise everywhere at about the same time, this seems very unlikely to me.
Well, I take your points. Obviously there's substantial room for a diversity of opinion on this stuff, and certainly tantalizing hints of extrasolar civilization (like the "Wow!" signal) indicate against my position.
You know, but weird synchronicities do happen. Newton and Leibniz independently developed calculus almost exactly at the same time. Edison and Swan invented the same lightbulb.
Just sayin'. Like I said I take your points.
Why would we expect to notice evidence of civillisations unimaginably distant from us.
Well, they shouldn't be too distant. The Fermi paradox is that
even assuming a relatively low rate of Earth-like planet formation, and
even assuming a relatively slow rate of evolution of complex life forms, and
even assuming wildly different timescales that intelligent life could evolve on, and
even assuming the incredibly narrow span of time we've been able to look, we should
still be up to our nutsacks in alien civilizations. Our galaxy should be a very crowded place but it's not. I suspect that's because we're the first ones to arrive at the party.