The kind of attitude and approach you have is exactly why people are in lower ranks, and will complain about their DPS and games being decided by this and that and anything instead of themselves.
Lucio is amazing in metal ranks by the way, he can pretty much duel any character including isolated tanks, give great utility including a team wipe saving ultimate and where people play slowly his healing is more effective should you need to do that to win instead.
Back to OP’s question; it’s everyone’s job.