to be honest if you main support there's only so much you can do with reinhardts who charge into Anubis A etc. Which is why I don't main support any more - I'll play it if I have to but you'll make much more of a impact as a good tank or DPS.
Very true concern, but that's where diplomacy and tact become more involved. It's really hard to hold all these abilities that assist others by being quiet. At the same time some people are just stuck sounding like an ass hole. My friend is an example of that, he is nice as fuck never talks shit, but when he tells someone to do something or try something different.. He automatically sounds condescending.
Being vocal, and commanding in a sense can play big dividends.. Or even making crucial communication combos, like letting that rein know.. If the rein is unwilling to communicate your team to go with the rein, it's still generally better to wipe as a group than to stagger anyways. Sometimes though as stupid as that rein charge was; you as support and people following could turn the tides of a fight.
A good example I was playing in sometime season 1, mid high 70s, and we had a rein even on defense, charge on cd. It was comical at first, but it was like laughing at a burning ship as we were getting stomped. He wasn't in coms, yet everyone was yelling and just all around panic. Happened on attack like one or two times then someone said fuck it, let's all go in... Sure enough we all went in and just stomped a push really fast. Fast forward to us back on defense, he's doing it still but this time the chat is filled with gogo and laughter instead of the original panic and anger. We had a pubstar hold on the trains outside of Spawn on r66. We didn't even have to move the payload to win it was so bad.
I know it's minut, but the whole point is to pick yourself apart and learn from yourself. It's better than putting your weigh of blame because of shit teammates I'm here ect. The no excuses! Even people like supports can make big plays, or game changing plays; but at the same time, in the same essence, most times shot callers on pro teams are the supports or tanks. Take Internet hulk for example, started as a dps then stepped to a tank; always the shot caller.
League has a similar thing with shot callers and in certain positions. Take c9 Hai, a great shot caller, but a lot suffered riding on the back of a mid carry that effected outcomes by scenarios.