I just don't think deep domain expertise makes you a better recruiter. You need to have deep domain expertise in recruiting with all its facets. Then, you need a working knowledge of the domain you are recruiting for.

Having a little experience coding is definitely a good thing if you are recruting software engineers. However, you don't need to be able to build a distributed system using AWS.

A good recruiter only recruits for a specific horizontal or vertical niche and knows enough about that domain to talk.

One way to extract value from that chain for an engineer would be, to offer tech consulting/teaching to recruiters.