I really don’t see how STS will make a plant herm more. I imagine breeders would have a much harder time selling fem seeds if it did
In general though it’s nice when you want to be more sure of your harvest, don’t intend to play with males, or can’t get a clone of the strain you want. I know some strains these days are clone/fem only, ike twenty20 mendocinos trainwreck. Supposedly it’s the most true to the original version of trainwreck available and they sell it fem only.