It looks like Twitter is bringing that feature onto its platform as the company has announced that they will be expanding the test of its downvote feature. Twitter had previously revealed that they were testing out the feature, so the announcement is basically them expanding it to cover more users.
We learned a lot about the types of replies you don't find relevant and we're expanding this test –– more of you on web and soon iOS and Android will have the option to use reply downvoting.
Downvotes aren’t public, but they'll help inform us of the content people want to see. https://t.co/g8LcTpQqDv pic.twitter.com/wm5MmdR4Xh
— Twitter Support (@TwitterSupport) February 3, 2022
That being said, keep in mind that the downvote feature on Twitter is slightly different from that on Reddit. The downvotes will be hidden from public view, so it is kind of similar to YouTube’s changes to its Dislike button. So instead of the downvote being used to inform other users on what the general sentiment is on the post, it will be more for Twitter to better understand what you like or don’t like to see.
Presumably it will then be used to help tweak the algorithm so that the company knows what kind of posts users prefer. If you don’t see the feature available to you, don’t worry as it is still being tested, but assuming all goes well with testing, Twitter should eventually roll it out to more users.