first off, when you tell them you are going to report them
they usually shut up...(there lil grudge is usually not worth it for them to be banned from the network)
and like pre-teaming yes they ruin the game, you take a loss and there is nothing you can do about it
and you have to "burden"(hhaha ok) yourself with reporting them.....
"if people want to watch the game let them go download the replay"
yeah umm noooo......
Hopefully

? if they cross the line they get banned not based on the mod's opinion but on evidence from the game.......Rule breakers make you lose the game whether its pre-teaming- bug abuse or what not but you get them banned......
So after dealing with a dead noob mouthing off, you have to burden yourself with reporting him on the website...
.
sure if would be nice if they didn't have any way/chance to do what you are complaining about but then you would be punishing the non-guilty parties....
if there ever was a lil rng tourney or something it would be good to have.....and it is a good idea but it has been suggested before I am sure and rejected...Honestly it's a fair suggestion you have
"you've still lost the game so it changes nothing"
-threatening to report works to shut them up more often then not
-same with all the other rule breakers the only thing that is possible to do without ruining everyone elses time is to get those players banned through a report....
-It changes nothing....like with pre-teamers and etc...Its kinda like crime, we can't prevent is all but we can sure make rules and punishments to prevent peeps from making stupid decisions....and it usually is very effective unless their grudge/insanity is that deep in, then they just get locked up/banned)
I am sorry reporting them is such a far-fetched idea for you I dunno what else to tell you lol
-What if they whispered/private chat the guy and told about the attacks, how would you/we ever know. you would have to watch the replay and what are teh chances you will do that...That is what concerns me...likely won't be reported cuz the player will never know