I think that with the popularity of 17.5 blinky 2wd buggy there is no choice but to have sponsored drivers. Sponsors get drivers to promote their products and I think there are a lot less 100% ride sponsors than many think getting a discount is what the majority get. point being if the sponsored drivers were not allowed in 17.5 buggy than there would be less parts development and r&d spent on the class, In my opinion the fact that the class is so successful right now is in large part of sponsored drivers at the local level they share set up tips, and help newer drivers learn a lot of the time these are the most helpful guys and gals at the track.
That being said that is where my thoughts of a lower speed spec class oriented class that is slow enough that the newer drivers are challenged to learn to drive and set up vehicles better, and at the same time making it a little boring for a more experienced driver will the race director have to kick some out and up on this class sure they will but that is the case with novice as well its ok. have heard the mention of needing another motor in the line up 21.5 or 25.5 but that is a non issue motors can be had new for 30 to 40 dollars for entry level motors ie trackstar and others of the like, this is nothing in comparison to a screw set so not an issue.
just my thoughts