In my opinion, matchmaking IS an issue and it does contribute to the trolling problem.
1. Premades - the premade team often leaves the random guy out of its strategy and communication (he's not on vent/skype with them).
When things go wrong, the random guy will distrust his team and the premades blame him, justified or not, for the failure.
2. Level discrepancies - matching level 12's with or against level 30's is bound to cause problems because of the runes/masteries and gaming practice. The lowbie is often overmatched, and then the high-levels are complaining about the noob.
3. ELO - using ONLY this one parameter to match skill levels is simply insufficient.
League's ELO is not derived from individual performance, but based on a team effort. Bad teams can lower someone's ELO below their actual skill level, while good teams can carry a bad player to undeserving ELO heights.
All 3 points can lead to general frustration which often turns to raging, feeding and quitting.
In summary, improving matchmaking will improve the trolling situation!