I started my italian Steemit / Reddit / Digg-like website more than 10 years ago, when everyone had a blog and all bloggers wanted to get their visibility. Facebook was in a very early stage and not popular at all (at least in Italy), people were not talking about social networks yet and content aggregators like mine were a very good way to grow visibility and traffic.
Also, search engines were not as smart as they are now and by then they were not able to identify news sourcesthus indexing content aggregators very well driving a huge amount of traffic to them and, indirectly, to websites that published contents on them.
Pretty much like it happens with Steemit, contents that used to get more attention would make it for the home page / category pages and get a lot more attention getting upvotes, comments and reads. Since people were making money from advertising published on their contents it was pretty clear that some of them would have done pretty much anything to break every rule and try to push their trash contents to the home page.
(image source: https://steemit.com/steemart/@ocm/steemit-hd-wallpaper - 
After a few weeks running our website was clear to us that the algorythms that made contents popular had to be very smart and go far beyond upvotes and comments. We worked a lot on it before letting the website proceed "alone", this is what I would suggest to website like Steemit to make its website work:
- Don't give upvotes such a big importance when deciding contents ranking. Upvotes are given by humans, most of them don't even read contents, a big part of them will just give upvotes to receive upvotes, pretty much as a trade. Friends will vote friends. If you just rely on upvotes to decide if a content has quality it just won't work.
- Spend your time on building algorythms that understand how users behave. Your main variables are: reads, upvotes and comments. Not many. Users that posts tons of short comments really give nothing to the community. Users that are able to give 100 upvotes in a minute didn't read a line of your contents. Users that spend more time on articles are valuable, since they are probably reading them. Users that just publish posts and don't interact at all with other posts are not real community members and probably just spammers.
- Give different weights to user actions. A spammer interaction is worth a lot less than a real user interaction. This is not a democracy, we don't want every content to get visibility, we just want the award the best.
- Grow up your influencers and your best users. They drive the whole system and community, they use your website exactly how it's meant to be used, they make good contents emerge. Reward them and don't reward just anyone who is writing tons of things or doing thousands reads or upvotes a day. Your best users will grow up other influencers.
- Update your home page / category pages often. Nobody wants to see contents that are a few days old on the home page, not even if they drove a lot of interest. When your userbase grows a lot it doesn't make sense to keep the same contents on home page for more than a few hours.
- Keep bots out. There is not bot yet who is able to understand if a content is good or not. Bots don't have time to read, bots can't write well, bots don't like John Steinbeck.
- Never make anyone know how your website's mechanics work. Or they will tell their bots. Anyway, people should not be interested in mechanics, people just want to read good contents and want their good contents to be read. Spammers are interested in mechanics.
- Give a bad experience to spammers. If it gets to hard for them there is a chance they will go away. Again, this is not a real democracy. This is a good-quality-content-driven democracy.
Some of my suggestions might be unpopular, some of them might be known to the most but a few of them are still making Reddit work. Anyway, I hope they might be useful to Steemit or anyone who's running a Reddit-like website.