The things which killed QuadrAphonics in the mid seventies was partly the complexity of the different formats, each requiring their decoders, and the VAT hike to 25%.
However, the manufacture of cart's able to access the discrete 4 channel stuff did lead to better stylii. Mine was an Onlife (early Dv or Koetsu?); a moving coil, but probably high output (can't remember).
Only the RCA discrete records really gave a worthwhile 4 channel experience. The SQ and QS records were just glorified stereo, i.m.o.