Totally agree.I guess for me it depends on my role.
I dont really mind not getting kills when I am playing a support role, I usually try to avoid getting the last hit when I am support and the carry is next to me or close to the target. But if I am playing Carry and I see some idiot range support constantly doing his hardest to get every kill it gets me mad.
When I play a support like Lion I step the hell back and SUPPORT. I don't care if I end up with 0 kills. As long as I help my team.
When I'm playing as a carry and Witch Doctor is taking more kills and last hits, it can be annoying.