The system is biased against Barbarians.
Of all the tilt-types that Riot outlined in their tilt... thing, Barbarians are the only type whose natural response to in-game stress is explicitly against the rules by default.
That doesn't seem very fair to me. Just because we represent a minority of the playerbase doesn't mean our ways of dealing with stress are less valid than yours.
And don't talk to me about "Vent Bot." Vent bot is useless during a match when I'm being actively flamed and singled out (which is exactly when I feel that urgent need to vent so I can get my mood back in check and focus on the game) because if I go afk to vent at Vent Bot, I get reported for going afk. If I vent, I get reported for venting. If I say nothing, I see nothing but red and hyperventilate and continue to play like trash which just gets me flamed even more.