League's community isn't toxic in itself. I don't think I met a toxic person in my last 20 games, and regarding trolls - no matter what online game you go to you will find people that enjoy games by being an clown so to speak. Difference is that people take league way too serious at any ranking below the top 1-2% and you believe that your way of thinking should be the only one because you want to be the best.
And league is probably the last place I would ever find a keyboard warrior. This isn't twitter my friend.
We are not a Toxic community, it becomes toxic in the eye of the beholder because they want it to be.