Probably the same people who came up with bike fitting based on plumb bobs, measuring tape, and lasers. Looks high tech and fancy but bike fit along with saddle fit has so many variables that using levels, plumb bobs, rulers and lasers along with mathematical formulas is actually an oversimplification. Fit has as much to do with mathematical formulas as your fitness level and muscle build.

Example: I ride the exact same bike I did two years ago. I was out of riding for an extended period of time due to an injury. the bike was set up for my previous level of fitness and the fit was dialed in perfectly. I have been riding for the past two weeks and cannot get comfortable. What was perfect two years ago is quite imperfect now. Same bike, same geometry, same saddle, same person, same weight..... different fitness level.

No mathematical formula or plumb bob can adequately determine the right fit. It may get you in the ball park and may be a good starting point, but it isn't the be all end all.