Fact: this is not true because they are used all over Europe and the world.

I have seen DPCs in several countries I visited, including: Italy (including Venice), Austria, Germany, Monaco, Belgium, Poland, Hungary, Romania - just to name a few.

Here is a short video we created, showing some of the damp proof courses we saw during our conservation training in Venice, Italy.. Damp proof courses are in use even in Venice - in one of the most protected cities in the world.