I do it from time to time and I feel like it's a mix of several things (1) it's counter culture, (2) it's early internet culture, (3) aesthetic/uniformity, (4) laziness, (5) carelessness, (6) a power move, (7) "hyper rationality".
And all of these contribute to it being a power move.
I use all lowercase on platforms where I share original content because I like the aesthetic of lowercase letters. They look more harmonious to me. I only use uppercase when using acronyms because I think they're recognized quicker by their shape.
Oh no! :) Yes, I use all lowercase on Twitter and Eksi Sozluk mostly. I don't write in all lowercase on Reddit, HN, or Quora, or forums, etc where different type of capitalizations mix up. I find non-uniformity less pleasing to the eye than proper capitalization.
I also write my emails with proper capitalization too, for similar reasons.
Not a power move at all! It's just that people who are this smart, whose brains operate in a higher dimension than you can possibly imagine, won't waste precious mental cycles on silly uppercases just the rest of us commoners.
Speed. The fact he even decided to Tweet/Xeet during a period of personal and professional upheaval is notable on its own. I’m cool adding in my own capitalization as needed. Or maybe I could past it in ChatGPT!
I've always seen it as a way of peacocking. A way for people to make themselves stand out from others. But I think it also stems from a mindset of "I'm aware that professional communication involves proper capitalization, but I'm not going to bother because I don't feel the need to communicate professionally to the person I'm typing to"
I'm fine with it as long as everyone is typing in lowercase. But if the culture of a company or community is to type a certain way, there's some level of disrespect (or rebellion) by doing the opposite.
And all of these contribute to it being a power move.