Phosphorus actually plays a bigger role in leaf and root growth than it does flowers. The supposed relationship to blooming is likely an offshoot of the myth about high-P "bloom boosters", which actually worked not by phosphorus content itself, but through the addition of inexpensive P-compounds to the formula, the nitrogen was diluted, lowering its concentration, and "allowing" the plant to bloom normally.
About 90%-95% of an orchid is water. Of the remaining dry mass, roughly half is carbon, with nitrogen, oxygen, and hydrogen existing in the 1-5 percent levels. P, K, Ca, Mg, & S are in the next tier, at 0.1%-1%, with everything else being in the ppms.
That was part of the basis for testing the K-Lite formula, but I'm actually not that big of a fan of using tissue analysis as a guide. For example, a plant will take up as much K as it is given, through "pumps" that offset normal osmotic pressures, so the high K content of a plant does not mean the plant "needs" it. If tissue analysis was a good indicator of need, then I obviously need more cholesterol!