First of all, I find it pretty awkward to get "anonymous opinions" on such a volatile subject. It's even worse that the survey is extremely short and is a yes/no followed by a "Choose One" for the reasoning.
Now onto topic : I feel that Player Moderation is not somethign really wanted.
First of all, players are obviously biased/subjective, because they're living beings with a brain. What this means is that the acceptable content, once player moderation kicks in, no longer reflects Riot's preferences but now reflects moderator's preferences. There is a massive margin or what can/cannot be considered off-topic depending on who's judging, and it gets even larger when you try to judge if it's acceptable. At that point, I feel that the oficial forums would no longer bear its true meaning. In my opinion it works on Reddit, because the subcommunities are basically international waters. It's not a community created/used by Riot and where Moderators are acknowledged. It's a player-driven community where Rioters are welcomed/acknowledged.
This brings the second point : backlash. Right now, when your content gets moderated, it's by either an employee of Riot Games (aka a Rioter) or a subcontractor (so still Riot-approved). You can create the backlash you want, they can always justify it by "We don't like what you are posting, if you want to post that kind of things, use another game's boards". At that point, there is no real possible answers, since it's basically the game kicking you out. If you get moderated by a player, there will always be a chance of power abuse for their self gains, removing posts from someone they don't like, self-righteous moderation (someone is flaming in game, you judge all he says on the forum much harder). All things like that, and in that case, you can appeal to Riot. This would create another dozen tickets per day.
Otherwise, we already havea form of player moderation : votes. If you feel that a post is obnoxious/useless/out of context/erc., downvote it. If it'S 100% unacceptable (an embedded video of murdering a chipmunk and feeding it to skunks), then you can try to contact Riot directly to get it out ASAP. OIne of the reason they chose to go with "reddit-style" is because it facilitates auto-moderation without requiring to elect a few elite users.