It plays out in other places, too. I've noticed that, since moving to Slack, the quality of electronic communication at my company has taken a serious nose dive. I think precisely because Slack makes it nearly impossible to have a deep conversation over a long period of time.
I've also noticed that the quality of discussion in face-to-face meetings tends to be inversely proportional to the number of people present. The more people, the quicker you need to be to speak if you want to get anything out there before the flow of conversation moves on and whatever you have to say becomes a non sequitur. The less time you can take to compose your thoughts before presenting them. The people who place the highest value on measured speech generally don't open their mouths at all, unless someone puts them on the spot.
The worst incarnation of this phenomenon that I can think of seems to be Twitter. Twitter doesn't host conversations. It hosts a conversation-themed massively multiplayer live action game in which participants compete for scorekeeping tokens known as "likes" and "retweets".