To be honest the biggest amount of toxicity I've seen in this game comes from the casual community, players refusing to learn, rejecting advice/leaving instance when advice is given and being disrespectful to those who give it, players who do not take into consideration the rest of the party and treat this game as a single player game, all of them are far more common than the "You're trash l2p idiot" kind of player.

Also I've noticed a huge amount of those players are healers (curebots) or single pulling no mitigation tanks