Because the symptoms of hypokalemia range from ZIPPO to cardiac arrhythmias and because any "excessive" K is eliminated, unless the GFR is less than 5-10% of normal, the chanced of developing hypokalemia from diuretic use far exceeds the minute risks of potassium supplementation.
I would agree however natural supplementation would be preferred BUT the total amount of K which is BIOAVAILABLE in ANY modern day food stuff is inconsistent at best.
Interestingly while some BB may attribute the vague complaints of cutting (weakness, cramps, malaise, muscle "twitching" etc) to "dehydration", they are often surprised to discover their serum K is LESS than THREE meq/dl (normal 3.6-5.0) This is particularly true of those using diuretics, IME.
Hey I'm not here to re-invent the wheel, but to perhaps provide another viewpoint from a medical perspective.
Regs
Jim