In 1969 BDSM was given its name. Usually looked at as B,D, & SM. This covered all areas of BDSM back then. You were into some form or combo of bondage, a disciplinary/power exchange type dynamic, and/or give/receive pain. If you were not into the D aspect, you were there for the sex and kink (SM). In the 90s, the internet changed a few things in this lifestyle. One being that BDSM became B/D, D/s & S/m. The D-type/s-type dynamic was unnecessarily added to the acronym. The D in BDSM stands for discipline, and that is where the power exchange is. We give our D-type the power to discipline us. Discipline is when the D-type trains the s-type to act or behave in a specified agreed upon way. This is often enforced with reward/punishment to encourage certain behavior to continue, or changes that need to be made. You do not have to have a reward system or have punishments as part of your dynamic. How you handle your s-type when discipline has failed is up to you as the D-type, and what the s-type has consented to.
This small change really doesn’t matter, it doesn’t change what BDSM is. Just unnecessary, and redundant. Had someone actually done research on what the D meant, D/s would not have been added.