I think another problem is that communicating by text in twitter posts. Its very hard to tell how serious someone is being. No facial expressions, mannerisms, or hand movements to guide. Like they could be making up the most absurd reactions, typing up a storm, and people will take them seriously more often than not.
Twitter is worse than other platforms because the format is really contrived. The 280 character limit doesn't give people space to write a nuanced, fair, well thought out response to things.
Also, if you contrast twitter and reddit, I would say that on reddit, everyone is kind of on the same footing more or less. Anyone can post a thread and if the content is interesting, it can rise to the top, then every response in that thread also has an equal chance to have visibility. The design of twitter is made so that masses of people follow some small number of "influencers", and these people have an outsized voice. There is no upvote or downvote, it seems to be largely based on how many followers you have.
The fact that there's no specific topical discussion groups I think also really amplifies the toxicity of the platform, because twitter can suck a bunch of people who have nothing to do with the discussion into the flamewar, as a way to increase "engagement". On a platform like HN, you have discussions about programming, and they're split into threads which people can choose to read or not. Reddit is split into subreddits on a variety of topics. It doesn't actively try to rope random people into some bullshit drama they have nothing to do with.
And uh, fun fact: twitter is not profitable, more than 15 years after they were founded, 8 years after their IPO. The stock has basically gone nowhere. It's a wonder they're still here, despite their lack of innovation and lack of business sense. IMO, the world would be better without this platform, but uh, I guess once your tech company gets past a certain size, it can never go bankrupt?
You should check out r/politics. It's primarily progressive and is as if the worst Twitter opinions sprang to life, became Twitter users, and got a larger textarea. Twitter does have the concept of topics, but it's mainly a mechanism for virality, which is tags. It's well known that Twitter users will witness an event emerge online, converge on a tag, and all compete for the edgiest quotes to get into the news reactions.
