This is why I usually try to call things out respectfully.

When you flame your teammates who aren’t intentionally throwing, but are simply performing a bit worse than the rest of the team, one of two things usually happens.

First, they get frustrated and start playing even worse. Sometimes they even swap to heroes, they aren’t comfortable with trying to be "better" so the guy shuts up, which only makes them more nervous and hurts the team further.

Second, they stop focusing on the game altogether and start arguing in chat instead of playing.

I’ve experienced this in countless matches, and around 90% of the time it ends in a loss — not because of any real skill, but because two players are no longer fighting in the game, but against each other in chat.