I've always felt that DevOps became a function/team partly because companies and especially SWE's started complaining that they were spending too much time "doing Ops work" and product/business started demanding more features for which they running out of cycles. And add to that the burnout from being on-call (especially if the dev team is relatively small and you have to go on-call every 2-3 weekends).

For most HR departments it is a role, it even has a career path.