Why can't people count to 5?

so many people with worse math skills then a 2 year old..

so many people that dive on to 5 enemies with only 4 of their team near them...

and then they say "please group up" "wtf where were you?" GEE IF YOU DIDN'T KNOW WHY ENGAGE 4V5???

as if everyone has a 10 second teleport cd or something?