There actually aren't as many breeders as you might think. Certainly not the numbers of people who breed, say, wyandottes or orpingtons or Ameraucanas. Many of the true heritage breeds are listed as more rare than these breeds. Also, it may be because they are difficult to breed to standard, with so many pieces to get right.
But, they are the sweetest birds! They have more personality than all of my other breeds. Nothing not to like!
I've known people who have decided against them simply because their eggs tend to be smaller than other breeds or the modern hybrids.