The problem is without proper map warding and mini-map awareness, it's impossible to know that it's just three people. I know this because 70% of my ganks as Kallari come from random scrubs bull-rushing two or three of my team for a fight and being unaware that there's an invisible player trailing them the whole time.
I love those moments. <3
So...I guess I actually shouldn't complain. XD
But even still, when you have no one to support you in any way and you charge in anyway...I wouldn't try it even with a completed Sparrow. But I play cowardly.
Mostly, it's Rev scrubs that think they can kill everyone and end up dying badly. New hero syndrome. I've had too many battles with players like that recently. And it's disheartening when the match snowballs in half an hour.