I have absolutely no problem with people playing bad, terrible or are feeding not on purpose. But i hate players that never push their lanes.Even players with 6/1 stats or something that never push lanes are terrible.
So they get a kill, what happens after it? Nothing, since they have to spend 60s pushing a lane. Why would you roam around getting picks, when there are no objectives to take off it.. When you could just farm up and push lanes and pick on people out of position after doing that and grab easy turrets.
Though having 250cs after 20-22min as adc freefarming is the only +side.
Also played karthus few games back after not having him played for over a year, 500+ cs in a 60 min+ game.. First time i had over 10k gold in my bank I couldn't spend, after already buying pots/oracle for 30 mins.