[MrFixr55]

Hi 462Ron,

I don't know why, but ever since before Consumer radio, they were using triodes as detectors, either grid leak, grid leak with regeneration (1914 Armstrong Super-Regenerative patent or Biased Detector.  The famous SE1430 and IP501 Shipboard receivers used a single triode as a grid leak with feedback.  It seems that Diode detectors were not used in Consumer radios until around 1933 or so.  The 1930 RCA Receiving Tube Manual (RC10) does not even discuss diode detectors.  This is interesting because the "Fleming Vlave", Ca 1904, the first vacuum tube ever invented was a diode, used as a detector in radiotelegraphy. 
The first Diode detector / 1st AF Amp combination tube, the RCA58 was available in 1931 according RadioMuseum but not used till 1932 - 1933

The US Navy Basic Electronics (Van Valkenberg Nooger and Neville, John Rider, Publisher) states that a Diode Detector has the least amount of distortion, followed by the Biased Detector (AKA Power Detector or Plate Detector), with the grid Leak and superregenerative detector as having the most distortion.