The question is whether that pays off in the end. That is, do Elsevier and others' papers have the bar high enough that it's absolutely not worth browsing and reading papers outside the commercial publication, or if it's just laziness and convenience acting up by placing trust in these academic publishers. The academics should be aware of the money and power game involved in commercial publishing, so they should be in a position to judge whether there is value to be trusted in it.
See e.g. https://theconversation.com/why-i-disagree-with-nobel-laurea...
So publishing on your own site on arxiv isn't sufficient on it's own, some curation and gatekeeping is essential for academic publishing to work. However, this is not a service that Elsevier et al provides for their payments, this service is provided by uncompensated reviewers from the community.
On the other hand, the ratings are used by the evaluators of science e.g. funding agencies which won't (and can't) evaluate results directly but need some trusted proxy to separate random ramblings from acceptable science, and the prestigeous journals fulfil that function.
Just uploading to the arxiv will not guarantee that your paper has been reviewed.