IMO, that's very likely an internet myth that began when someone decided that because Primo (or Winny for that matter) is a DHT derivative then it somehow is a DHT precursor. This logic does not hold. Remember, Var is a test derivative... and so is estrogen (I believe...).
Dbol made my hair fall out in sheets. Winny and Primo had no effect on my hairline whatsoever. Again IMO, AS's that are hard on the harline either (a) convert to DHT via 5-AR or (b) are hard on the hairline in proportion to how androgenic they are.