I can understand for supports that it would not make sense to take it but for any other lane going down the far left tree wouldn't it be the best to take? As long as you kill all the enemies at least once you are going to deal more damage than if you took the other masteries.
bc killing all 5 of the enemys is a bit hard to do as a single person because lets say you are right and every lane besides support took it then all the enemys have to have atleast 4 deaths and those 4 deaths has to be from everyother champ
Because the likelyhood that you will get those individual kills is less likely unless you are on a burst champion or adc
Because some champions take longer to get kills than others and some people play more passively. Of course it's the best to take if you can easily kill your entire enemy team early on, but some people prefer the early game advantage of double edged sword or the other mastery that is better for people with low amounts of kills
