They want to make the product appeal to all users and not just techy ones. And If I product managers or CEO or whoever can print his message bold he's happy.

Very few non techy people know what markdown even is. (From my own experience asking friends etc.)

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.)