Actually, I find that an all -purpose saddle, a properly fitting one, does have its place. More designed for the rider not striving for a career in jumpers or eventing or dressage but one that is interested mainly in the pleasures of technical trail riding with the occasional natural fence, dabbling in dressage, and/or low level hunter pacing. Maybe not optimum, but certainly suitable as well as economical for the hobbyist.
If one is more inclined to compete, specific saddles are more in the line of necessary depending on the level of skill one wishes to achieve.
Regardless of type or brand, the fit of the saddle, to rider and horse, is critical.
Sure there's right and wrong but mostly there's just a whole lotta different.