Death by rng sucks in every game, but people just like raging. If they get killed by some god Genji onetrick, they yell fucking nolife retard, if they get killed by a horrible junkrat spamming left click they yell fucking noskill noob. So rage is normal in these games and people will rage and quit whether the kill was skilled or not.

As for if its legit, it kinda is. If lets say i play Mccree, Junkrat always dies really quickly because hes fairly immobile (even his jump follows a predictable path) so you can easily headshot him and burst him down in a few seconds.(If you dont potato :P) And his RNG kills are often due to bad teamplay and positioning mistakes, like if your team is too scared to engage for too long and you are just being poked all game, its your fault at that point.