i think all dogs are lovely.
i would never call a doodle (or any other dog) a 'designer' dog simply because dogs are not predictable.
if you get the most health tested pure bred dog from the most scrupulous breeder out there that is not 100% guarantee of the dog being true to the typical breed characteristics or healthy (though usually such a dog also comes with a money back guarantee, and breeder assistance with training issues).
Most pedigree dogs will generally be like their parents, and generally conform loosely to expectations. My dog, though, is nothing like the typical dog of her breed in character. but i love her anyway. she is at least the expected size, shape and coat-type.
if you get a x-breed you have even less guarantee, as they don't throw true. no guarantee even that you are getting what the breeder says...(hopefully you will at least be getting a puppy that belongs to the mother you see with it). it is even less 'designer'.
in general OP most dog vendors aren't people i'd want to buy from, and most puppies come from bad circumstances - the very nature of the scrupulous breeder is they wouldn't breed very much at all!
so, raining on your parade is a consequence of some people who care about animal welfare and don't want you to buy from a puppyfarming scumbag, knowing there are very few doodles that come from breeders fulfilling basic welfare requirements, never mind health testing, after care and all that.
and in some cases they're just being snotty.