|Plastic holds are infamous for rotating (at the worst possible time it seems).
Plastic rotates easy because the back of the plastic holds are smooth, low friction plastic. Adding to the problem, plastic holds have some "give" to them. Crank hard on one side of the hold and the plastic can "bend" away from the wall just enough to reduce friction.
On a typical plywood wall, synrock holds just don't rotate. The backs of synrock holds are as rough as 80 grit sandpaper. Also, Synrock is many orders of magnitude "stiffer" than plastic. Just a little tightening and these holds lock into place - permanently.
This saves lots of time moving holds around since you don't have to waste time cranking your holds down, all the while worrying if you've got the thing tight enough.
It also saves wear and tear on your T-nuts. The socket cap screws used to bolt on holds are grade-8, so they are harder than the steel used in T-nuts. Excessive tightening "cuts" into the T-nuts which can reduce their life span.
Because these holds don't rotate, we can sell amazingly "large" holds like the big pill and cruxmaster that only need one bolt to hold them securely in place. No need for an extra drywall screw to keep the hold from rotating.