People go insane whether you are playing poorly or not if you aren't doing exactly what they want as though it were the only way to win. I would have the highest score in almost every game and still get harassed by someone. Also if you want to play competitively get a team to do that with. Randomly grouped people is not competitive play it is one or two douchebags demanding that people they don't know do whatever they want.
Cant say iv had this experience often. And i play online games pretty much any time i am at home and not on forums.
And Randomly grouped people can be VERY competitive. That is if you can get a high enough rank/score for the game to place you in games with people off equal skill or higher. But when you are average and being placed in games with other average or sucky people then yeah often it can be not so competitive especially in TEAM games because just 1 guy that sucks or does not understand team work can make the whole team lose. Which yeah that isnt very competitive when its near impossible to win due to a shit player. Hell thats not even fun. Its actually the very opposite of fun for me.