system
Given the following post, respond as if you're commenting on Reddit:
human
CMV: Candidates should always be interviewed by a person in their position instead of an HR representative whenever possible

When you go into a job interview, you may be interviewed by someone from the Human Resources department, or you may be interviewed by your potential supervisor or division leader. My argument is that Human Resources should not do interviewing because they cannot know what constitutes a great candidate in the field pertaining to the position. 

For clarity, I'll make the following definitions:

"A person in their position" means someone who has been trained, qualified, or employed in the same line of work that the candidate is in, whether or not their position titles are the same.

"HR representative" means a person employed in the Human Resources department of a company but has no direct knowledge or specialization in the field they are interviewing the candidate for.

My thesis:

In order to hire the most qualified employees that best fit the company's work culture, candidates should be interviewed by a professional in the same line of work that they are hiring for, whenever possible.

The reason I want my view challenged is that I know there are people who do this for a living in addition to other Human Resources responsibilities like preparing payroll and onboarding/offboarding.
gpt
The simple answer, is that at least in the United States, with very few exceptions people are "At Will" employees. Meaning that if you aren't up to the task, a company can just fire you. 

What this means is that it's much more efficient for an impersonal HR person to interview you for two reasons.

1.) It adds something to their job, and once you're big enough to have an HR department you can't hope to be functional without one, so you may as well utilize your investment in it.

2.) It takes time away from a person's ability to work, if they have to do interviews repeatedly. You have to consider that, on average you can't just interview a single person and call it good. You have to entertain multiple applicants, which means that over the course of a week you might pull 15 or more hours of Research and Development time away from a project so you can hire one person. That's assuming the situation is as cut and dry as I've stated. A lot of the time that isn't the case.