Surely age is relevant though. If something is very old it's priority should increase as it's in danger of never being fixed in the lifetime of the product or being superseded when the feature is re-architected / removed.
Is the point of priority to fix that issue or to improve the product? If it’s the former, old bugs should increase in priority.
If globally improving the product is the goal, deprioritizing (or leaving alone) old issues is probably more reasonable. “We’ve lived with it for this long; how critical could it really be?” In this case, the risk of never being fixed is a feature, not a bug.
