I'm sorry, but what users ?

AFAIK Facebook, Instagram, Snapchat, Twitter doesn't have a WYSIWYG editor.

Are there some hidden users that send font size 30 all capitals red colored text in Times New Roman to each other ?

Office productivity tools do typically have WYSIWYG editors: Word, Outlook, Gmail, ...

Thank you, it didn't occur to me that some users are actually using slack to replace e-mail communication.

Step 1: google “how to make text bold in Slack”

There is no step 2, that’s literally all you need to do.

I think you overestimate the tech skills of your average user. I know so many people for whom typing "how do I X" in Google is too difficult, and will flat out refuse to do it.

That's not to say that I think we should be dumbing down software for them. In fact, we should be doing the exact opposite.

You're not wrong. I suppose all I can say is that software companies have every right in a free society to cater to people like that to the detriment of technical users... and I have every right to vote with my feet and wallet.

(There's a reason OpenBSD and macOS are both alive and well.)