By emphasizing a past date, the headline (and article itself) gives the impression that the record was set over 5000 years ago, and that this is the first time the gold/silver ratio has been higher than at that point in time. "Since 1940" would provide better context, and would not prompt such confusion. It seems likely that the reference to 5000 years is specifically to sensationalize the news and draw clicks.

As an illustration of the absurdity of such a style, one could equivalently put "in over <x> thousand years" in the headline of pretty much any metric that has been on an upward trend through its history.