It's not so much that the system that needs change. It's perfectly possible to have an interesting community on Reddit, although those are a dying breed nowadays. Reddit has a number of powerful and flexible tools for mods to use, and there are (on paper) ways to get around the downsides, such as making an alternative subreddit.
It's just fucking corruption, through and through. No vote brigading - unless you're a lefty sub, then it's allowed. No racial discrimination, unless you're /r/BlackPeopleTwitter, then it's allowed. No self-promotion, unless you're a corporation that pays money to astroturf, then it's allowed.
Rules that make sense (such as no death threats) are applied inconsistently. If you're the wrong kind of person you can't even joke about it. If you're the right kind of person, by all means keep wishing death on Trump/Putin/J.K Rowling. The same with illegal activities, and doxing, and hacking, and ban evasion. To say nothing of admins outright colluding to destroy certain subreddits.
There's nothing at this point that can make Reddit a good website, but it would be a halfway decent one if they actually followed the system they built, instead of wielding it selectively to fuck people over.