There is a difference between setting solutions and decal solvents. I use setting solutions regularly when applying decals. They are pretty benign. Solvents, however, are "medical care" for difficult decals, or applying decals to difficult surfaces (extreme complex curvature, ridges, deep panel lines). Solvents by their nature partially dissolve decals, and, like any medical care, involve risks. I only use solvents for problems, and then start out with minimal application, increasing as needed.
Also, there is considerable variation in concentration and dissolving power between brands of decal solvents.