I've been on a climb that I was doing solo. I came up behind a man and woman ahead of me on the climb. I got to a point right behind the woman. I would have waited lower down, but the only decent rest spot was right behind her. I then waited for her to finish the climb before I climbed up. They went off on me. All I have to say is I didn't force them to climb faster, and I felt comfortable with the situation. I figured I was in the biggest danger for an accident, but they felt like I was making the situation unsafe.
I think part of the problem stems from them being totally unused to solo climbing.