This is a very good question, and there is really no right or wrong answer to it, it simply depends on what you're looking for in a bird. Obviously if you go to a breeder you're going to buy a young baby bird, or sometimes a juvenile bird, and usually these young birds have been hand-raised by the breeder, instead of being parent raised and not tame. When you go to an avian Rescue to adopt a bird, they are typically not baby or young juvenile birds, but rather adult birds that have been surrendered to the rescue by their prior owners for one reason or another. That's not to say that you don't occasionally find very young birds at rescues, but typically you will only find adult birds at rescues, some of which are not tamed and we're not hand raised, some that are tame and were hand-raised. You typically will not adopt a bird from a breeder, because most breeders are doing just that, they are breeding young birds to sell the potential buyers. The only birds that you could potentially adopt from a breeder would be retired breeding birds that they no longer want, or potentially young birds that did not sell right away and are a bit older; however, the still is not really adopting because you're going to end up paying the breeder for the birds. Adoption typically means that you are taking in and providing a home for a bird that is in need of one because their prior owners could no longer keep them.
There are literally tens of thousands of adult birds in rescues across the country who need homes. There are more birds in need of homes then there are dogs in shelters and rescues and a lot of states. So essentially adopting a bird from a rescue is no different than adopting a dog or cat or any other animal/pet from a shelter or rescue. Many people believe that with the number of birds in need of good homes, that people should never go out and buy baby birds from private breeders or pet shops. This is a personal opinion, but it does have merit to it obviously. So there is no right or wrong answer as to whether the person who told you that you should only adopt a bird from a rescue was correct or not, it's just personal opinion. Is it better to adopt an adult bird in need? Yes probably. However, you have to do what is right for you, your family, and your situation.
There definitely is such a thing as a good breeder and a bad breeder when it comes to birds, just like there are good and bad breeders of dogs, reptiles, rodents, etc. It is absolutely crucial that you do your homework if you are thinking about buying a bird from a private breeder or from a pet shop, you need to look at reviews, comments from experienced owners who have purchased baby birds from the pet shop or breeder you are looking into, and you need to do your research to know what questions to ask any private breeder you were thinking of buying a baby bird from. For example, you need to ask them at what age do they pull their baby birds out of the nest box and away from their parents to start hand raising and hand feeding them. You need to ask them at what age do they start weaning the birds onto solid food, and whether or not they practice full abundance weaning, because if you end up with a breeder who knows nothing about breeding birds and simply decided to put their two birds together to make some money, that's when you can get yourself into serious trouble. An experienced breeders of birds very often and up Force-Weaning their babies simply because they don't know any better, and this typically results in birds who have severe neurological issues throughout their entire lives. So it's very very important that you research any breeder or pet shop who breeds their own birds, and make sure but they are an experienced and reputable breeder of birds, and you know the correct questions to ask at the time you're ready to go and look for a bird.
Now the upside to adopting an adult bird from a rescue is that you get to spend ample time with a bird who has already developed their personality, and you get to see whether or not you are a match for the bird and the bird is a match for you. You don't get to do this when you go to a breeder or a pet shop and buy a baby bird; you simply get what you get. I have worked at an avian Rescue for over 8 years, and typically on average a perspective adopter spends at least three or four visits with any bird they are thinking of adopting, with each visit lasting at least 3 to 4 hours. So by the time you're ready to make a decision about whether or not to adopt a bird from a rescue, you have a very good idea as to whether the bird is a match for you and vice versa. Very often people find that birds in a rescue end up choosing you, not the other way around. More often than not people come in to the rescue to look at a specific bird but they saw online, and they end up adopting an entirely different bird that they would have never considered prior to coming in to the rescue, because the bird simply chose them. So this is a very very important advantage that you have when you adopt a bird from a rescue that you don't have when you buy a young baby bird from a pet shop or from a breeder.