Fact: damp proof courses are one of the most important defense mechanisms against rising damp and they are used all over the world.
Just think for a moment. Up to about a hundred years ago buildings have been built without damp proof courses. Obviously, our forefathers have observed the rising damp phenomenon and they tried to mitigate it by laying large boulders or rocks at the foundation of some buildings to keep the capillary effect away as much as possible. But because most buildings have not been built at such "high standards" of the past, from 1877 damp proof courses became mandatory in the UK. As a result, from around the early 1900s more and more buildings have been built with DPCs, usually using bituminous felt, lead or slate.
Damp proof courses are the only technical solution against rising damp that have the POTENTIAL to fully solve rising damp long term by blocking the upward movement of water and salts from the ground. Now, how well various DPC technologies work and how long they last, that's an entirely different matter. But some of them have the potential of achieving what they promise: to completely block the rise of water.
Any other solution NOT solving the problem at the wall level, but addressing other areas - such as the soil, the finish (the wall surface) or the environment - don't even have the POTENTIAL of solving rising damp permanently because they don't block the water off the wall, which just keeps rising.
Multiple solutions can be combined for more efficiently combating rising damp, but damp proof courses have a very important role in this sense as their effect can not be substituted by any other solutions such as drainage, replastering, heating and ventilation etc. All these solutions, although beneficial, at best they can only "manage" the problem of rising damp by reducing its severity or by covering up its symptoms - giving building owners a few years break before the problem reappears and needs attention again.
If possible, these secondary solutions must be done in conjunction with a damp proof course.