No, you would not be stupid to the formally trained welders, but you might be ignorant of some concepts that they have learned, because that is the proper way to use the words. Now if you are incapable of ever learning those concepts, either on your own or in training, then they would probably think you are stupid.
Ok, examples then:
My in-law was most definitely stupid. It was not about any kind of learning style. She just had mental capacity issues. She had the emotional mental capacity of a 15 year old(as diagnosed by a doctor) and could not grasp simple concepts. Watching a movie with her was like watching a movie with me 7 year old, and she asked the same kind of questions. The kind of sublties most alduts could grasp easily. She had wealthy parents and went to a good school, but could not tell you what half of 14 was or who our first president was...inability to learn. She was kind of annoying, but I had a lot of patience with her, because I know it was not her fault. I have met many people over the years who were different levels of stupid. Saying there are no stupid people and it is just 'learning style', is like saying there are no fat people it is just 'body type'. It's true for some, but not for all.
I get annoyed with ignorance, especially willing ignorance, and it has nothing to do with agree with me. If you have a well thought out view, then good for you; I really don't care if you agree with me or not. The best example of this is politics. There are so many people who go to the polls and vote for a party because their parents did and everyone they know does. They are completely ignorant of what either party actually represents, and when talking to them they describe their values and beliefs to you about politics and the views are actually in line with the opposite party from the one they voted for. I tend to be more conservative, but I have a lot of friends who are liberals and know the issues inside out. I don't share their views, but I respect them. I have also met some conservatives who were not conservative at all, but they voted that way because they always had and their parents always had. This is the kind of stuff I get annoyed with much more than my in-law.