Contemporary radio has always been a copycat business. There were as many "Fake Blores" as there were "Fake Drakes". And after that, "Q Format" ripoffs and xeroxes of KIIS-FM.
Actually, it's not less important. PPM measures what you're listening to, but you, the listener have to remember what it is you like and where to find it. Mnemonic devices like station names have been shown to have better retention when it comes to imaging than a set of four letters beginning in "K" or "W".
There were several dozen stations that broadcast in Quad, at least part of the time. The BBC is credited with the first Quad broadcast in the summer of 1974. Among commercial stations in the U.S., most of the activity happened in 1975 and 1976. Classical and album rock stations were more likely to broadcast in Quad, though more mainstream pop stations like KIOI in San Francisco and KKDJ in Los Angeles, did as well.
Hearing Quad required more than two additional speakers---it required a quad decoder. That alone was $250-$400. That's the equivalent of $1466 to $2346 in today's money. And then the cost of two more speakers. And that's assuming you had a fancy enough stereo with a free input and output for the decoder and two more speaker outputs. A lot of record buyers and radio listeners didn't.
More people might have done it, including me, if there had been one standard for Quad, but there were three, QS, SQ and Quadradisc. I was waiting for standardization so I could buy one decoder...but the market evaporated before that happened.