The problem with this (very interesting and fun) theory is that Earth would have to somehow be the very last planet to develop such intelligence amongst the large list of planets within detection range, which seems unlikely.
If that's true, only a very small fraction of planets with intelligent life would land in the window where we can observe them.
Another option is that you might have many civilisations that are just as intelligent, and just as developed, but not in the same fashion - imagine 99% of intelligent species out there are more like dolphins than like humans.
Or their atmosphere is just a bit more hazy than ours, so they are not aware of the night sky filled with sky, so with less curiosity to imagine the world outside of theirs.
That makes it possible, not likely.
For any population N > 2, it's less likely that you'll be last than that you will not be last.
I think that generally I agree with you, but I would tend to say you have a small (but >0) number of things that would have huge long term ripples.
Many people became educated and even advanced science before the government got involved in education.