> I know I'm being super conspiratorial here but why wouldn't all forecasters predict just between 30% - 70%? That way if they're "right" they can take the credit for it and if they're wrong they can say "well, we weren't that wrong". That's probably what I'd do anyway...

For anyone making many predictions, you can analyze the outcomes to see how accurate those percentages are.

For anyone making few predictions, you should never trust their track record even if it's technically perfect.