Selfdefence is something very different than sport/training. It can be most of the things sport is; fun, good workout, competative etc.
But a big diffrence is that if you sell selfdefence programs the customer wants it to be effective. Prisons, psychiatric wards or the average person might not have the time to become a great grappler, boxer and being able to defend against knifeattacks.
Selfdefence is so much more than just technique. It's about attitude, mental preparation and a course of action if something happens. If you give me 60 minutes I'll probably be able to teach a group of 50 how to eyegauge, bite and twist someones neck in order to escape if they end up on bottom, or at least keep the offender busy until help arrives. In 60 minutes I might be able to teach 20 people how to do a scissor sweep but I doubt more than 10 will do it in sparring. If they sparr with strikes I would be surprised if anyone without previous grappling experience managed to perform the sweep.
You are absolutely right when you say that there is no way that someone will be able to grapple without actual grappling practice. The point is that people that pay for selfdefence classes wants selfdefence and not being taught how to grapple, throw a perfect jab or a roundhouse kick.