Definitely cheaper: PM rods, even though strong enough for the typical person, are cheaper then stronger forgings. A rod isn't a wear part like a gear. Conrod sits with some nice bushings or bearings. Gears engage each other.
The material has its place like any. In a place where the part itself takes the wear(like a gear or pump), or certain types of stress(like a rearend), it sucks. But, it saves money and lasts just long enough for most.
What PM really is, "its just as good as, but not quite and a helluva lot cheaper".
My PM days for the automakers are long over, so are my diamond cut custom billet gear making days. Guess what I would dream my vehicle to be made out of?