Thanks for discussing.
Honestly, it depends on what you are trying to coney. If you are conveying whether current times are like past times, or whether a current rise is equivalent to a past “bubble.”
On the other hand, if you want to convey the powerful effects of compounding, then a linear scale will show how gradual annual changes can create dramatic rises to unsustainable levels in the present and near future.
That might make sense for things like oil consumption, which is a physically limited resource, but the price of gold is not a limited resource (because it is simply a reflection of the lack of value of a dollar, which can go as close to zero as those in control wish it to.)