Purpose of external recruiter in final interview?

This week I have a "final interview" and am failing to understand the purpose of the external recruiter attending. So far I have had: * Initial discovery meeting with said recruiter - one hour and so

This week I have a "final interview" and am failing to understand the purpose of the external recruiter attending. So far I have had: * Initial discovery meeting with said recruiter - one hour and so in depth on behavioral questions I wasn't even sure what next interview would be about * Interview onsite with existing team/hiring manager/HR member - one hour and all behavioral, essentially got grilled by hiring manager to the point I did not expect to get asked back * Assessments - 2 hours Now I have been scheduled for a final interview with the CEO and the external recruiter I met with first. As far as I understand these are the only other attendees aside from myself - why would that be? A couple of other details to note: This is a senior position for a relatively small company so the extent of interviews isn't all that surprising to me (should it be?) The hiring manager did make me uncomfortable and I already considered withdrawing my application, but have decided to see it through for various reasons. I am familiar with this process though I have never heard of this before so any insight would be very helpful!