The interviewer's job should be to determine whether, and how, the candidate would succeed in the organization.

No, that's the job of whoever is making the hiring decision. The interviewer is providing signal for that person / people.

in my opinion that disenfranchises the rank and file who should, and usually do, have as much interest and voice in the organization's future as the hiring managers

Ask a technical question or two and assess the candidate based on their reply.

How can you assess this when divorced from the resume, or is this technical Q&A purely "people skills" and how is that possible?