I agree with you, I think the other person was an idiot.
Even on trails, when I pass I give plenty of room - a body size for joggers and walkers, more if the space is available, and more if the person seems uncertain. Give plenty of space to bikers to.
But I don't yell out on your left. I don't like it because:
1. Some people only hear "xxxxx left", and they think they're supposed to jump to the left for some reason. One person I almost hit.
2. Many people are wearing headphones and can't hear you anyways
3. It's annoying to do and it makes my ride less enjoyable. If it wasn't for
#1 and
#2 I might do it anyways, but those are a problem.
Rather than a bell, I do wish someone made something that constantly made the noise certain expensive hubs make when you coast that "fishing reel with a fish on it" noise. Would be nice for people being able to hear me behind them. Never been able to find something like that though.