I tend to agree as well (for what it's worth). One needs to be maniacally stringent when hybridising, to keep the female scape untouched as well as the male. All it takes is for one insect, or even strong air flow, to move pollen from a male to a female, or from one male to another. Also, if one female scape had several different male plants used to pollinate it, there's always a risk of transfer. Covering flower heads from the moment they appear is the only way to make sure contamination doesn't occur.