I don't believe I am incorrect, but I don't think you're wrong, either.

Just like rescues, all shelters aren't the same. Many shelters are underfunded or don't have appropriate resources. High-kill shelters down South have barely any staff to assess the temperament of dogs because they are jam-packed with animals especially in the spring and summer. There are great dogs there that don't get the training or temperament assessments they need

I live in an area where the SPCA hasn't had to euthanize for space in years, animal shelters in the area import dogs from other parts of the country to adopt out because there aren't enough intakes or strays, and people have to be on a waiting list because there are so many people who try and volunteer at a dog shelter. The ARL down the road has volunteer trainers to work with dogs before they're adopted to. It's great, and I know it's a luxury that shelters in this area have that others don't. As a seasoned dog owner who's done a lot of research, I'd be more than confident I'd be able to find a great shelter dog at these organizations if I wanted to, but I'm also pretty confident I'd miss a few.

Why? Because so many dogs shut down in shelter environments. Sometimes it's the barking. Sometimes it's the stress that barrier aggression causes. Sometimes it's just a lack of routine, or lack of exercise. I foster dogs for a private rescue, and even the best dogs go through an adjustment period before their true colors start to show.

I agree that OP can possibly find a great dog in a shelter environment (if you reread my post, you will see that I said that) but with their inexperience and not knowing what is available as a resource, it carries risks that they should consider and research as to not fall into the same situation as the Mari adoption, especially if they do not have shelters that are as well-maintained like where you and I live. I say this knowing that I got my dog at a stressful, loud environment, and if I had just randomly walked in that day she wouldn't even have been on my list of choices to adopt, but I trusted the rescue who matched us based on our needs.