This is really a half backed idea and maybe other people would have better solutions, but this morning I was glancing over /r/cheatatmathhomework, and came across the post of a user wanting a confirmation that the solutions of the equation x^3 + x = 2 are 1 and (-1/2)i(sqrt ± i). So far, so good. But then user rustu-ruekce replied "The only real solution is 1. [...] You've stumbled on the complex solutions which aren't useful at all". And that's the moment when the psychopath inside me wakes up.
In the above case, one may argue that rustu-ruekce was trying to help but is simply misinformed. Fine. But what if I wanted to prevent misinformed people to reply to a question I am asking on any user forum? In this case something like a variation of karma would be needed.
Depending on the website, karma, means various things, but it often reflects the level of engagement and contribution of the user. I wish that those websites also had a variation of karma that only measure the level of... competence of the user. So now two things needs to be clarified: (1) how it is computed, and (2) which effects does it have on the website's dynamic ? I am going to call this new measure lumi (a word totally made up).
The way lumi is computed/modified is that every time a user with higher lumi than you upvote or downvote anything you have written, then this, respectively, increase or decrease your lumi (using a formula that I do not need to make explicit right now). Easy. Then, everytime a post (for instance a request for help), is submitted to the site, the original poster can decide that only users above a given level of lumi can reply to it. Lumi is a real number, but to simplify the task of the original poster, a break down such as ['anybody', 'helpful', 'respected', 'wizard'] can set the threshold.
Now, in the particular case of reddit, the interesting thing is that a user has a lumi number for each subreddit. Being a legendary wizard at /r/cheatatmathhomework, for instance, should not be the reason why you have wizard level at /r/photoshopbattles. In other words, you need to prove your worth at every subreddit, if you want to have access to (more exactly to be able to contribute to) higher level posts of those subreddits.
I cannot imagine why somebody would put a lumi threshold for a /r/awww submission (even though it is possible), but for subreddits I care, I would actively work at increasing my lumi (by contributing informative replies) and then ask the web app to hide any reply made by lumi users of level say half of me. This would protect me from any idiot who created an account just to sabotage my discussion with a stupid troll.
This could also work for YouTube, by which one could choose one of various levels of discussion. Each video has several comments threads and you can only access (and/or contribute) to those threads matching your lumi level. I would set YouTube to helpful level for all video. No more Pascal wasting his time navigating through hundreds of idiots before finding the one guy who is not a total moron. Problem solved.
Now, as you can imagine, lumi could have interesting unintended side effects :-) For instance, you are unlikely to increase your lumi level on any subreddit where everybody is an idiot (they would not be able to recognise your genius and upvote you). Or you are unlikely to raise it on a politics related subreddit where everybody has exactly opposite opinions as yourself. Not to mention cases where a user with a high lumi level could be driven out of the elite circles by a group of other high level users (for whatever reason). But, you know what, that's how real life works...