The idea is you can use less titanium in the application you would use aluminum, but this has limits. If your ladder was .200” wall thickness, you might in theory get away with a .070” titanium for the same weight, but you start running into mechanical stresses or assembly issues or manufacturing.

Titanium is useful when you need internal volume - most recently as an example by Apple. Aluminum was fine, but had thick walls. Steel allowed thinner was but was heavier. Titanium allowed for thin walls and more internal volume, but at a higher cost.

Basically, if you don’t have a size limit, aluminum is great! But most things have size limits, and titanium allows you to trade size for cost.