I've wondered why Twitter seems far more toxic than Reddit (certain now-banned subreddits excluded) and I believe the downvote is a powerful tool used to achieve this, along with Reddit's community-style moderation, even though that can border on toxic itself at times. I wrote about it here a little while back https://unlikekinds.com/article/trolls-and-consequences-what...
Also, as somebody else said here, the discussion takes place "on" your identity, as opposed to reddit where you have your identity and then go out to places to discuss.
I have separate accounts because my different interest belong to different bubbles, and I'm afraid they would outrage each other. Also, one is mostly for consumption and the other is mostly write-only.
(My ideal social network would have each user in full control of their identity page - a bit like MySpace or the old Facebook. And then you would be able to go and create pseudonymous subaccounts for discussions. The system would only show what you want to share, e.g. "this handle's main account is female, on the site for >3 years, and has ~5000 rep". This way you'd have anonymity but still some measure of trust.)