In my area, SCT was the most popular class about a year ago, then it was Mini-Truggy, but now most folks are running 1/8 eBuggy... this progression seems to be related to several factors where I believe the 1/8 classes are getting longer 10 min mains and the 1/10 classes are only getting 8 min mains, so negative reinforcement is partially to blame. There's no reason why ROAR can't allow 3S for 4WD SCT which would eliminate so many electrical issues that plague the class. Folks get frustrated with overheating their electronics and less durable options in 1/10 in general, it's no surprise to see folks opting to run vastly more efficient 6S setups in 1/8 eBuggy without any concern for temps, power, durability, performance, etc...
If you want the truck classes to be sustainable, then you need to relax the lame 2S restrictions imposed on the class.