Trials rewards are generally superior to most in-game loot, which incentivizes players to queue in the game mode for a chance to get that loot. If you are not a top player, the current system gives rewards consistently only to 3-stacks, where matches are much more difficult than solo queueing. Losing as a solo (especially with bad performance) gives almost no rewards - just some glimmer and XP. This leads to frustration, because in addition to getting stomped almost every game due to matchmaking being seemingly random, you are also gate kept from getting better gear. To add insult to injury, some people t-bag just to mess with your mental when they see that you can hold your own or feel like you are enough of a threat to their win streak. It's reasonable to correlate frustration with toxic behavior. It may not be possible to remove all toxicity in the game because there are some people that will break the rules just for the sake of it. Still, I'm tired people being -blam!- to each other over some artificial scarcity in a video game, and at the end of the day it's the developer's responsibility too to create an environment that encourages good sportsmanship and mutual improvement.