When I want to develop, I don't want to work on operations, and vice-versa. The context is completely different, and it conflates two completely different mental and authorization models.
Added to this: no one can really define what the devops buzzword actually means. Is it configuration-as-code? developers-doing-operations? or something else entirely?
DevOps is about not thinking like this. When developers produce deliverables without a production operational context and 'throw it over the wall' to Ops, it leads to recurring systemic issues. By making developers responsible for what they produce, they feel the pain of their decisions during 'development time' and will learn to make more operational-friendly software.
The other aspects such as automation and coded/immutable configuration came about because of DevOps and is now also part of it.