Don't think into the mechanics of how a go-kart handles and drives from your "experience" with indoor karting. Indoor karts are a different animal than say a sprint kart. Indoor karts do not have the same diving characteristics as sprint racing karts. Indoor karts use slip and slide as you describe to overcome the lack of chassis flex.
If you feel that learning to slide a kart is not beneficial to a driver, think again. Your young driver is out on the road on a stormy day and the car starts to slide. With no experience this situation will usually end in tragedy for the driver, the car or both, with experience this situation could be handled safely. Over coming over-steer and under-steer is no different on a kart or a car, it takes skills. Learning these skills is priceless!
Go-karts have been a training ground for race car drivers since they were invented. Most modern drivers have come through the ranks from karting to where they are now. As with any other sport, kids will develop the skills necessary to progress if they are capable and it is their desire. There is no other way to get kids into motorsports at the age of 5 or > than through karting.
Take them out to the track to watch a few races. Locally in SoCal there is LAKC, IKF, PKC and to the south SDKA, all running sprint races. LAKC, IKF and SDKA have kid kart classes, PKC does not. If they show interest enroll them into a training program. If they like the sport great, if they don't you only had to spend a couple of hundred dollars to find out. Another suggestion is to learn as they learn, so you understand the lingo, mechanics and technologies.
PM me with your e-Mail address and I will send you a draft-copy of my eBook "The Ultimate Beginners Guide to Go-Kart Racing".