This idea of devrel as an enablement role makes total sense. Rank and file devs are the true subject matter experts so its their voices we want to hear.
However, devs usually have enough on their plate with their job, and generally prefer to code rather than create content, so it would need to be incentivized by management.
Another challenge is that content creation is really a skill on its own and requires confidence. Even with enablement from a devrel, companies would have to invest in educating their devs on how to blog, speak etc.