The typeset article is what you'd see if you download the .pdf from, e.g., Nature. .
It's the manuscript with all the stuff that distinguishes an article from one journal to another (where is the abstract, what font type, is there a divider between some sections, etc.). Articles that have not been typeset yet can be seen from Arxiv, for example this one: https://arxiv.org/abs/2409.04391
No, that's not what I said. You're right that journals, to some extent, also lends credibility to the publication, but it's not the source of credibility. What I said was that an article published in Nature will have many more views than an article published on a random WordPress blog.
Again, saying that researchers "agree to have it that way" ignores the structural difficulty of changing the system by the individual. The ones who benefit the most from changing the system are also the ones most dependent on external funding - that is, young researchers. Publishing in low-impact journals (ones that has a small outreach such as most open-access journals) makes it much harder to apply for funding