I think supporting changes with your elo. People tend to be the most toxic (from my own experience) in lower divisions, such as 5 and 4 of any rank. Honestly, I feel like jungler's and mid get the most flack, but that's just me. There's a difference from someone being toxic and someone questioning your methods, however. If a kill is secured... and I press q as Sona out of nowhere, I'm not gonna expect my ADC to be "happy" about that. They wanna win the game, I wanna win the game, we all wanna win the game. A kill on a Sona or Janna early doesn't win lane. Also, even a few creeps can be the difference between a level up (an all-in), a good back, etc. I'm so guilty of this!
The above only really applies in ranked play where people wanna win. If you ks in norms I don't think anyone should care, and if they do they're idiots. Seriously, Lich Bane Sona and Trinity Force Leona are fun.