I'm always really happy to hear about people doing their research and supporting a responsible, ethical breeder looking to breed dogs better than the generation before because that's the future for dogs.
If everyone bought rescue dogs, there wouldn't be any dogs pretty soon...
I also support the rescuing of dogs and I've fostered dogs myself. But when I buy dogs for my family, they come from ethical responsible breeders, regardless of whether they breed pure or not. I've had to jump through some serious hoops to get my dogs, more so with my crossbred because the breeder was deliberately breeding for loyalty and she feels her dogs can't be happily rehomed. But that's how I think it should be. My dog is a huge part of my life, training every week even after 4.5 years and I take him everywhere so it is very important to me to know my dogs' relatives and understand the values of his breeder.
Don't let anyone make you feel bad about researching the type of dog you wanted and being selective about who you get it from. You are the reason that dogs have a chance of being better next generation than what they are now, and in fact have a positive future at all.