I am really sitting on the fence, so I haven't voted yet.
This was initally prompted by a conversation I had with a breeder who is upset that a multibreed breeder has started up next to her, she has inferior cats of numerous breeds, and is undercutting everyone else on price.
Unfortunately she is actually GCCF registered but is not a responsible breeder in my eyes anyway. I don't think her cats are abused or anything hideous is going on, but she is flooding the market with poor quality cats to no-ones benefit apart from her own.
I think meemonkey is right though, in that limiting the number of breeds bred, wouldn't make any difference, the unscrupulous breeders wouldn't care and would still produce kittens for money and not for the good of the breed or for more importantly the good of the kittens.
I think though that there are quite a lot of pedigree cats being rehomed through breed rescue instead of placed in the local 'pound'. Rescue organisations tend to contact breed rescue as well when they have a pedigree cat so the small number in rescue is not an accurate statistic for the number of pedigree cats being rehomed.
"Jack of all trades master of none" is a phrase that springs to mind I think it is quite difficult keeping up with pedigrees/genetics of one breed without 2 or more different ones.
Elsa