To understand why their slider is useful, it' helps to understand where they were coming from with the Extra V1. They say with a traditional linkage system, you have a rocker arm rotating around a pivot as it pushes the shock into compression.
Confusing terminology aside, basically a falling rate leverage ratio pushes harder on the shock as it goes deeper into its travel. Which makes it challenging to design a good linkage system on a long-travel bike when you want to use an air-sprung shock.
[
Collection
]
[
|
...
]