How old are the people you communicate with regularly? I work with plenty of late 20 and 30-something professionals and they all intrinsically understand this phenomenon. I also work in tech, with tech savvy individuals, so maybe that has something to do with it.

What a bizarre take. Who do you work with? The majority of people I’ve worked with of all ages at various companies default to all-lowercase in casual communication, including some of the most intelligent and expressive people. As the other commenter said, it’s perceived as friendlier and more casual. Messages with capitalisation and completely correct grammar in these settings comes off as stilted and corporate.

I've literally never seen this in 15 years of working.

Perceived as friendly and casual by idiots.

That's needlessly aggressive. :-/

It just sounds that way because they used a full stop. /s

I'm really surprised at how defensive some people in this thread are getting regarding this.