The thing is people write threads to write a twitter thread. It's to increase their following. A good twitter thread will get a twitter account a few hundred new followers. This is literally just them working to increase their audience. And most of the time they're increasing their audience to sell stuff.
That really depends on the author. In my experience most IT-related people don't care about selling anything, they're just sharing knowledge. Even on the extreme, patio11 who would very much want to sell you stuff, posts threads every day, but not for that reason.
I have a love/hate relationship with both Twitter as my primary (for last while) writing outlet and threads specifically.
I love writing and love talking with smart people. Twitter enables both things. The activation energy for me to write a Twitter thread is much closer to "water cooler conversation with the world" rather than "write an essay that I hope to be read for 10+ years and will with more than 50% probability spawn an HN comments thread whose tenor will largely determine how happy I am that day."
The whole experience of writing on Twitter, both the perceived-even-if-I-know-it-isn't-real ephemerality of it and the lightness of tapping out on my phone or PC when between tasks, does something for me that essay writing cannot.
That's why I write threads almost every day. Strategically speaking, I hate it; a million words on Twitter would be far better as a million words of essays, or even any substantial fraction of that.
