I don't think you quite understand either point. Discing down is about learning to control the disc rather than having a bunch of discs to cover a bunch of shots. It helps iron out form flaws, and is a really good way to learn some of the things you need to throw far.
The point of this thread is again that you don't need 8 different overstable discs in every speed, you can make a disc work for you if you learn how to control it. The two concepts are quite compatible if you take the time to understand them.
^This.
Also, this thread would have never been thought of if more people spent some time on the DGR throwing assignments. "Right disc wrong shot" and the like. They'd have already tried throwing their Comet on the spike hyzer hole and realized that they didn't need a Gator, Whippet, Zone, and Firebird.
DGR Training Assignments