azaleas, no need for kanuma

Some expert tell me that the only substrate possible for azaleas is kanuma. Well, why is it that in the biggest azalea growing area in the north of Europe they ONLY use rough peat for millions of azaleas? I have planted these into baked loam 60 % and 40 % rough peat a couple of years agao. Do they look sick? The foliage could not possibly look heathier. Another bonsai myth crashed.