If there's no one on the path, I think it would be alright to train. How do you know that someone's going to pop up a few seconds later? You don't. It's just easier to train through unless you really want to waste a lot of time fighting all the mobs.
I never train people on purpose, but I have trained on accident when I don't know there's a mob following behind me or there's someone hidden somewhere. Not everyone trains on purpose, so I think people should start accepting the fact that not everyone wants to kill them. I know very well what it feels like to be trained, but you can't help it. Everyone is bound to train someone at least once, even if you don't know it happened.