Serious question: why doesn't whoever writes the POHs advocate LOP?
IIRC, Piper used to (and perhaps still does) advocate operating some of their products LOP. I'm fairly certain that in the '83 and later Warriors you could set the engine power using just the mixture knob.
The drill was to set full throttle and full mixture then lean the mixture, reducing the RPM to the desired power setting. They covered their arses to a certain extent by suggesting that if you ran LOP above 75% for extended periods, you might damage the engine. Other than that, running LOP was fine. Evidently the O-320-D3G (I think) has quite an even mixture distribution to all cylinders, allowing for a smooth ride LOP.
So there you go yr right and others. A major GA manufacturer from over thirty years ago more than happy for people out there to operate LOP, well and truly way before it became fashionable to question decades of engine management folklore.