That's a little bit different. One group of people thought the earth was flat, that wasn't the consensus of the entire world. Ancient greeks knew that the earth was round way before the Europeans decided to test that theory. But yes, I do agree that we do not know 100% all the capabilities of the Echo, but just going off of how it has been behaving so far, we can say for certain it has not shown that it can show us the future.
Also, I'm not so sure about the starshower triggering the Echo anymore. I mean, yes, in the 1.0 story the hero saw the starshower, and so did all the others in the Path of the 12. But if you started in 2.0+, there is no starshower. You just have the power of the Echo. Maybe for 2.0 it was simply granted to us by Hydaelyn? /shrug