With social media, getting accurate information out of user-submitted content is always hard. But there are steps that could be taken to alleviate this problem. Through the use of sophisticated reputation systems, where user reputation forms the bedrock for deciding which content should be displayed on the front page, we can ensure that high quality content is displayed most prominently.

This is a shitty way to build any form of discussion system where you want new ideas and real discussion rather than just a bunch of people everyone likes saying things everyone likes.

People who say things others do not like, even if they say it in a really nice way, will get pushed down due to the pushback from the community, and their content will never be seen, they will get less rep as a result, and will be pushed out. Meanwhile, if the community agrees with something, the idea goes up, and the person with correct opinions is the only one getting a place to speak.

But posts that have a large number of both upvotes and downvotes will be promoted just as heavily as posts that are universally liked.

This assumes ideas are contended, or debated, rather than disliked entirely by the community. Ideas can be incredibly unpopular, and incredibly hated at first introduction, then grow on people over time. This system prevents that from happening.

But the idea of a community where everyone only agrees with one another, and dissenting voices are promptly silenced

The idea of a community where your ability to speak depends on how much people like you sounds much the same.

Instead, all new subscribers start off with the same baseline reputation, which gives them little influence over what happens in the community. Over time, as they post content that the regulars like, they build up their reputation

Except they won't, because all the posts everyone is able to see will be from those with reputation, and those people will gain reputation at ever faster rates, pushing out everyone lower than them. Even an exponential model isn't going to fix something like this, because no sane amount of exponential increase will turn 1 or 2 votes a post into a user who can compete with 100 or 200 votes a post.

At Caucus, we want to give the quiet ones a fair voice too. Hence why we take into account the number of times someone has voted, or posted content.

Yes, because we should punish the active and dedicated users. Consider a person who is really passionate about a subject, and posts about it frequently.

if you arrive several hours late to a discussion, your comment has very little chance to make it to the top.

If you arrive several hours late, everyone has already seen the post, and there is nobody else left to comment in the first place, even if you put new comments as a higher weight, it isn't going to well promote new content.

Themed communities

Reddit has subreddits, CSS, automoderator. What exactly does this mean?

Promote/Sponsor features

Again, reddit has an ad system that does exactly this. Also having site-control of the content in a site designed to act as reddit is not a good idea.

No ads. No corporate sponsorships

Good luck funding your site.

Organically determined community leaders

Big words. Now lets see you actually find a decent, fair system to make this work.

And many many more

Great features there.