OP. it seems to me you are using 'a trainer' whether an in-person one or not- your puppy has been biting your arms, refusing to walk on lead without the leash in mouth and barking at you. So when you post issues like these and someone or many answer you, you are actually in many cases getting the advice of a trainer.
Or you could be getting advice from people who have NO CLUE how to fix the problem you are having.
Or flipside the other way around, a person could be very reluctant to say anything because what people describe and the reality of what's going on can be very DIFFERENT.
One thing I'll never forget was this girl in my neighborhood who would randomly (like 2-3 times a year) take her rottweiler for a walk around the block.
One time she was out walking the same time we were walking our dogs and we could hear her constantly telling her dog to heel. Constantly. High pitched whining and begging and threatening from owner nonstop.
Next thing we know dog went running right past us and heading for the hills. Owner followed her with a broken chain.
My sisters and I were agog because we'd had it drilled in our heads that training tools like a choke chain must NOT be used on a pulling dog outside of training situations. And then we also had it drilled in our heads that you never train your dog at level beyond where he can be successful.
Seeing some of the posts on this forum over the years, I've imagined situations like that when people complain about pulling dogs and switch to different and more powerful (more painful and/or restrictive for the dogs) tools to keep them from pulling.
What people post - it's a dog who pulls constantly and they can't control the dog.
What people don't post - it's a dog put in situations where they will fail and owners not helping the dogs be right.
No matter what people read on forums or videos they watch online, if they don't have somebody seeing what they do and telling them what they are doing wrong based on actual observation - they are going to keep blaming the dog.