ADOPT DON'T SHOP???
You can't claim to love cats and/or dogs and then be ONLY in favor of rescue! It just doesn't work that way.
If you truly love cats and/or dogs and want the best for the species, you NEED to also support the idea of responsible breeding. If the only cats/dogs you deem acceptable to own are the messes made by irresponsible breeding bought through the proxy of rescue or shelter, and you demonize the practice of preservation breeding, then what you're saying is that the ONLY cats/dogs that should have a place in this world are those bred irresponsibly. Those animals bred in mills or born due to owners not altering their pet or "just wanting to have one litter".
We should want - DEMAND - better for our cats/dogs! And that means advocating for the breeding of better cats/dogs. Those that can live long, happy lives. Responsible breeders spend a lot of time and money to breed healthy animals. They work to certain breed standards set up by respectable associations and they work closely with their veterinarian to make sure all adults and litters are healthy. Responsible breeders advocate spay/neuter for their kittens/puppies going to new homes and they spend time making sure the new homes they go to will be loving homes. Responsible breeders will sell with contracts and health guarantees.
Sadly, rescue organizations and shelters will always be necessary, but if we continue to vilify and discourage responsible breeding, we won't have any healthy cats/dogs left to enjoy. Both we and our fur babies deserve better than that.