In reality, upvote = I agree, downvote = I disagree.
However I don't think anything can save twitter from being a toxic platform.
What makes it especially toxic, I think, is its lack of separation of communities.
Reddit is toxic sometimes, but at least there is some separation: if you just want to talk about knitting, you can avoid the people talking about politics.
I think it's important to be able to have controversial debates in real life, as body language and audience response seems to keep people from being truly awful.
The Quakers have an interesting history of trying to facilitate such controversial debates. They have been involved in some contemporary ones too.
https://www.quakersintheworld.org/quakers-in-action/210/Inte...
It's concerning to me, how much of real life discussion we have lost due to the pandemic.