That's my general understanding too. More recently people have adopted it as a way to not look like Ai, I've had several cite that as their rationale. There has been a notable uptick since the Ai step function change at the end of last year, along with all the other patterns we see, such as the one that underlies this new HN rule.
I shouldn't have to burn tokens to read. Most input boxes and editors will handle the capitalization for you during auto-correct. It seems like people go out of their way to drop the caps.
Who cares about people with reading disabilities, let's shift burden onto the reader. My time is better spent managing my Ais.