Part of a comment from the linked site, please no rich-text. I always think when rich-text is allowed it is the first step down. Usually when that happens "ne'er-do-wells" start arriving :)
That would be terrible
Honestly though, that was also my impression until I saw the implementation. It's really conservatively applied, and doesn't clog up the whole screen with text and distractions. Eg. if Discord/Slack had heading sizes for standard messages, it would be pretty horrible for the user. If our only objection is culture alignment, I say they go forward on it. I'd like to have code blocks and (eventually?) syntax highlighting for posting quick code snippets.
When you hover over a message, the immediate options are emojis. Not reply, copy, but goddamn emojis.
I chuckle at the downvoting that does not address the issue. One might argue that it is a generational issue. There is an argument to be made that picture is worth a thousand words, but some things require precision that goes beyond ::eggplant::,::tongue::