She was talking about a topper for the embroidery - either a heat n gone or a soluble product. Said to use the heat type for things with a nap so it would never go away, but a water soluble for most everything else. Exceptions were for non fabric items (leather, vinyl, balsam wood).
Besides the issue with nap (which I understand) her rationale was that the movement of the embroidery foot was going to cause stress and wear on the fabric and possible stretching with knits - and the topper would eliminate that.
I plan on using my embroidery for enhancing quilts, so figure it might not be something I need to be overly concerned about since my base fabric would be quilting cotton.