The only time I ever see these things used is when a developer is writing their own blog in markdown. They can't be used for clients, because most clients will not want to write markdown. So what use do they provide outside of personal developer blogs?
Good question!
I've asked the same question to many professional bloggers (I run a platform for bloggers).
"Did you use markdown to write blog posts". The answer was a big NO. Most of them use the default WordPress editor (now Gutenberg). Some of them use Google docs and other 3rd party tools.
As you said, markdown is mostly used by developers for their blogs. I haven't seen many professional bloggers not using it
I'm a developer and a blogger. I still don't use markdown :D while blogging
I'd say Markdown is becoming the standard of writing on the web. If the client doesn't want to write in Markdown, they can use some tools which can help them convert the text to it, but overall it's their problem. Static websites have a large base of companies using them. E.g. Middleman was used and developed by Mailchimp.
Diego Bernal
Front-End Engineer
Bayu Angora
★★★★★
Markdown is easy and newbie friendly. If your client needs WYSIWYG (like writing on WordPress dashboard), you can integrate it to CMS such Forestry.