I blame the chat apps more for this tbh. Coming from a long history of using IRC, using separate messages is a completely normal way of dividing up one's text, and it was fine because N lines of text in a single message wasn't hugely different from N lines of text over multiple messages. For the most part, the end result takes up the same amount of screen real estate, and I honestly like being able to send out thoughts piecemeal in a more active discussion--it lets others start priming their response before I'm done, or read through it as it's being said, versus having to wait for a complete set of messages. It's really one of the differentiating features that made me prefer chat over email or forums back in the day.
Slack, Discord, etc. wander in and turned chat into a _product_, and specifically a modern mAxImIzE eNgAgEmEnT product. No fucking chat app should send as many notifications as Slack and Discord do default, and they also shouldn't return to the same noisy default every time you join a new server, but they do. There's a good reason for this: constant pings make you use the app more because human brains are easily distracted, doubly so when something has been crafted to grab your attention. This probably results in a mix of actual stickiness and garbage interaction stats that product managers toot in internal meetings to demonstrate how good their ping flood is to clueless upper management, but the end result is that the distractathon defaults are just accepted as the way things are.