Some of my friends are dog people. They will tell you about this breed or that breed like they are all totally different. Maybe they are.
The line of what defines a pure breed cat is in general very fine and subject to interpretation, the genetic variances between breeds is extremely small and many times personality “traits” exaggerated.
There are a few exceptions, as specially created breeds like Bengals or Savannah sometimes come from a single original litter (after many tries and mixes) and thus you can trace all individuals of the breed in existence to that single pair.
All cat breeds are created or have been modified from this original source.
You won’t find cat in Turkey that would pass as a purebred Turkish Van, or a blue short haired cat in the UK that would pass as a British Shorthair.
However, I think there is quite a noticeable difference between purebred and domestic cats, especially in character and temperament.
The most important thing to remember is when you get a cat, that’s going to be your companion for up to 20 years. It’s only right that some people prefer to pick out traits in this companion.
There’s nothing wrong with shelter kitties and I personally have had nothing but shelter kitties, but unlike some I’m not in favor of shaming or pressuring people who choose to pay a reputable breeder for their forever friend. Just as long as, you know, it is a reputable breeder!