You think they are eyewitness accounts even though one of them says it isn’t?
The reason given for a 70+ AD date for the Gospels is that Jesus makes a specific claim about the destruction of the temple. So it must have been written after, because there’s no way he could have actually known that, right?
That’s one reason given, but not the only one, and anyway its far more complicated than you suggest because the passage also appears in Mark which is often dated before then. indeed.