I can't speak for anyone else, but I don't really care where an agent is located, nor do I have any issue with companies outsourcing their call centers (it makes a lot of sense, really).

The non-US agents seem less familiar with the rules and issues can also arise when the agent may have never actually flown on United (or whatever carrier they represent). One example that comes to mind was several years back when E+ was fairly new to United Express aircraft. I was on the line with an agent in India who insisted that United Express planes did not have E+. Either he couldn't see it or refused to look, but it was plainly seen on the seatmap on my monitor. After a very frustrating and long conversation (should have HUCA but I'd already invested so much time booking the segments), he finally transferred me to a supervisor who assigned the E+ seats with no problem.

And just a couple weeks ago, I called and had this conversation:
Me: I'd like to book a RT award from LAX-HKG with a stopover in VIE.
Agent: Vienna? Vienna, Italy?!
Me: Well, it's in Austria.
Agent: You can't do that!

You certainly can, and allowing a stopover on a RT award is hardly an obscure rule. After thanking her and hanging up, I called the number I gave above. Reached an agent that I assume was US based (didn't ask), who had no problem putting in the flights I'd found and booked the itinerary with no problem. So that's why I suggested the OP call that number, regardless of which location it reaches, as it sounds as if he's trying to book something similar and reaching agents who don't realize it's possible.