I've experienced this a lot in the past few games I played where people literally pushed into the enemy team while being defender, instantly dying and shouting at me for not doing anything. Am I wrong here, or wouldn't it be better to wait...

I'm silver 3 and my current "main" is Omen but i'm not very good with his TP or his ult. So i wanted to switch to Brimstone but i never see him in high elo games so i don't know if he is viable ?