So, I am really bad at killing, like mega bad. I play support all the time. I just help other people who are actually good at killing, kill things. Even characters who aren't supposed to be a support I end up trying to play as a support. So then I get to playing with assassins. As you can assume, the assassin class is all about the kills. Their sole purpose is to secure all the kills that are set up by the rest of the team.
So what do you think will happen when me, super support player, tries to play a assassin? Well wonder no more here I am sure you will find that "Echo and Assassins don't go together."