Twitter is most useful if you’re interested in a niche and you want to stay current on new stuff. For example, my sister is a Ph.D. in ecology, focusing on marine biology. She follows other Marine biologists and when they publish new papers or lectures, they’ll post. Also if they’re looking to hire they may share that as well. So Twitter is a nice way for them to communicate publicly about what they’re researching. I follow software developers in the Apple world, and also some data science and behavioral economics stuff.
If I want to debate fringe lunatics, I’ll just go to the comments section of YouTube.