While I do find it unusual that a screening interview would be conducted by someone who reports to the position to be filled,…

This has become very common in my field. I may be interviewed by a hiring manager, potential direct reports, internal customers (like program managers & new business), and peers. That last one can provide the best view of what it would be like working there.

I've had a variety of people for the phone screens too. One thing that some people (e.g., kahuna) don't realize is that the phone screen is not just for the employer - it's also for the candidate to screen out an undesireable opportunity. As a candidate, I don't want to go all the way for an in-person interview if it's a bad match.

I usually insist on having a phone screen with the hiring manager before committing to travel. This gives both of us a clear idea of expectations. Also if the hiring manager is too busy to do this then I doubt I'd want to work there. One time I didn't follow my own advice and ended up after I was on-site that the job was a bad fit. I was annoyed to have wasted 3 days (2 days travel & 1 interview day) on a bad match. They did offer a position but not one I would take. So the idea of skipping the phone screens can result in a waste of time and $$ for everyone.