so are these like other fields don't use LaTeX but other formatting?
I can see for example if its' mostly word documents from source on that area of science maybe there's no point on arxiv like pipeline that builds from source.
wondering if it will ever converge there, like a wikipedia only about science/research but of all areas
Some of it is formatting, some of it is just field dependent. SSRN is commercial and "good enough" for many people. It (at least used to) advertise itself as a social network for social science academics. There's also SocArXiv[0] and others, which are purer extensions of the arxiv model.
Part of the issue is that the arxiv doesn't want every discipline in science, so a certain amount of duplication is necessary.