Even at .0006c (our current tech), the galaxy would be filled with (weakly self propagating) robotic probes after just 750 million years. Unless extremely long lived self-propagating probes just ... die out ... that implies no aliens older than 750 million years from our galaxy. It implies no aliens from the nearby galactic neighborhood within 3 billion years. That kind of implies we're all alone.
I have three wild-eyed theories: (1) eukaryotism is an unbelievably exotic step; (2) and/or the moon is required and ultrarare; or, (3) advanced civilizations eschew yellow stars for being inconveniently short-lived: maybe they prefer brown dwarfs, white dwarfs, or black holes for their energy gradient.