As you pointed out Drake's Equation does pretty much make EI a mathematical probability if not a certainty. There are however some issues such the fact that some of this extraterrestrial life might have gone extinct already, way before life started on Earth. Billions of years of time is a long time
Yes, extraterrestrial life will not be visiting us if it's the equivalent of our dinosaurs or ooze, or like you said, extinct already. The chances of our time lines overlapping, and then our populations finding each other, are basically slim to none.