As someone who once had a reasonably large (>5k) twitter following and has essentially given it up there are a few factors I believe contribute it being far more unhealthy than HN or Reddit:
- It's tied to your real identity (and your real ego).
We all know that pure anonymity creates 4chan, but being associated with your personal identity means that every "engagement" on twitter feels a bit too personal. On both reddit and HN being pseudonymous means you still have some sort of reputation, but up and down votes are always about how a community interacts with your ideas, not you personally. Even worse than facebook, you're primarily being judged by people who don't even know you. This sets up every tweet to being a basis for being personally attacked by strangers.
- Short message length abolishes nuance. On both Reddit and HN the most successful posts are often long, nuanced and typically make several points to draw a conclusion. This is impossible on Twitter. You can't discuss the nuances and values of both R and Python for data science work, you can only make flippant, reactionary remarks.
- Might makes right. The follower system is horrendous for any kind of reasoned discussion. There a plenty of well known, adored people out there that make factually incorrect assertions but it doesn't matter if they have 100k followers, they win the war for engagement. Forget about cases where it's not see easy to establish factual correctness.
All of these combine to make an environment where to feel good about your self you are naturally driven to write flippant content that will attract more followers (so nothing too controversial for your audience, no having complex opinions, you should fit into an easy to market 'identity'). You can resist this, but this is what the platform has been designed to encourage. It's sad how many thoughtful people I've met on Twitter that inevitably get sucked into this trap and start shouting out engaging garbage so that they can continue feeding that cycle.
Despite my complaints about trends in the HN community, several small things help a lot:
- largely keeping pseudonymity
- Hiding up/down vote counts! It's quite possible for one opinion to have an order of magnitude more support than it's opposition but both idea can be near the top and no one knows.
- Giving all comments a temporary boost in the page position to give them eyeballs and a chance to be heard.
Making votes invisible is probably the single most brilliant thing HN has ever done to keep this community sane. You can see "people agree with/like my comment" without comparing yourself to everyone else.