When does this game get really toxic?

I've had quite a few friends tell me that League is one of the most toxic games ever, but as far as I can see getting my levels up, I haven't really seen much toxicity at all. In fact, most people don't seem to use all chat at all except for complimenting each others' plays, non-toxic banter or saying gg at the end of a game. Sure, games often end in stomps, but no one gets really angry or anything about it.

So, when do I end up getting all the toxic people? Is it when I hit level 30? Or when I hit ranked? It seems to me that sub-30 games are a lot more friendly than I believed they'd be.