Suspension Wizz kids -- What's up in my forks??

[RichDesmond]

In this case it isn't the spring being shorter that's lowering the bike. Not directly anyway. That spacer is between the underside of the damper rod lip and the topout spring. That's preventing the fork from extending as far. It's lowered by the length of the spacer. (Well, technically the length of the spacer times the cosine of the rake angle. )
The spring has to be shorter so it's not creating a ton of static preload in the new configuation.