O.K., makes more sense than a ride height number.

That doesn't sound way off. But still, it's tough to compare numbers to anyone else's without a standard tool like this:
With a standardized number, you can talk to Jeff Nash, Bruce Meyers, Scott at Desmotosport, Nick at Munroe Motors, etc. etc. (all folks who've raced or run race teams at the national level), and get a better feel for where you are. Measuring to the tail is fine for a ballpark number, or just for keeping track of your own changes, but you loose the ability to compare notes since most tuners use the gauge.