lol simply coz dota is a team game?
whats the point of playing without proper teamwork from your team? the answer is pointless!
lacking of 0.5 % of your participation warrants an instant loss, its that intense 
but true for alot newbies, before they manage to learn, they will be discouraged by alot scoldings etcs..lol
for me i dun mind playing with newbies, but some of them juz like to nose pick while you're playing hard...man no conscience ..back to 

and the dude above, for wow u dun need to rely on people as much as dota, you can nose pick and take your sweet time in guild wars n raids and at the worse u get is pked