You are right, cat breeders typically only breed purebreds (pedigree) because they have value e.g. to buy a purebred/pedigree costs a lot of money. Cats that are not purebred don’t have any commercial value.
In the UK most pet owners don’t buy purebreds but rather get moggies (cats of mixed traits) which are usually given away free by other pet owners who didn't have their cat neutered and have ended up with kittens that they then want to find good homes for.
In our case, our friends had a Rag Doll female cat that although not a purebred was predominantly Rag Doll, they got her free from another friend; and likewise the father was a local Tom, who himself not a purebred was nevertheless predominantly Maine Coon. Consequently, most of the kittens had strong Rag Doll and or Maine Coon traits.