^As I've said many times, I do not dispute the possibility that it can happen that way. I am merely pointing out that it doesn't invariably have to, that that's just one of the two possible outcomes.
We just have different takes on the matter. I do entirely understand what you're saying. You're picturing the whole tapestry of, say, 10 generations. Your input into the system is that you change one person in the oldest generation and hold everything else constant. The expectation is that because you're holding everything else constant, the output you end up with is a very small difference in the present.
I just have an entirely different view. For one thing, you can't hold everything else constant. So, you change one person in the oldest generation, and this results in entirely new people who behave differently, do different things, and, importantly, have kids with different people than the the original timeline. Now you have a person who didn't exist originally having kids with entirely different people and that repeats over 10 generations and the differences just magnify. You can't hold everything constant, all of those interactions are going to change everything about the people.
I do agree that all of these changes in people may or may not change the flow of history. You might have fairly similar history in broad strokes just with a bunch of different people. Or, you could possibly end up with a radically different history. I think that depends on the specific people that no longer exist versus the new people who now do exist. I agree with you on that standpoint that the broad strokes of history don't necessarily need to be different within a given time period.
Although, I'd add that the probability of a major divergence increases with the amount of time because the change in people increases exponentially. So, it's probably just a matter of time before they produce a major divergence.
Mr Awe