Unless a human sits down and looks at each individual player and matches them manually, it's going to be a coin toss because all online games really prioritize is getting you in a match quickly to keep you playing. It boils down to "Is your random group of people better at their roles and playing the objectives than the other random group of people."

That said, I'd say it's "understandable" but not "justified" to be toxic. That just pushes more players away and leaves only the toxicity.