Word neither does writing exceptionally well nor does it do layout exceptionally well. Nor versioning. Nor Visual Basic development (alt F11 I think), Wildcards, Document automation, Macrorecording, Styles and Templates, Image Editing, Spellcheck, Grammarcheck, Collaboration or Focus Mode.
I know all of these from my time as a teacher—except Focus Mode they copied that label from us much later. My job was teaching kids how to use MS Word and its functions for years and all these functions have their bugs. Data loss and file corruption are everything but uncommon due to the complexity of everything that Word does, and that you don’t experience that (maybe with a more limited use, by mostly just writing) is great for you. But it doesn’t mean that it doesn’t exist.
Sure, if you know how to avoid the bugs you can get things done. But they are bugs nevertheless.
It does a lot and it does it in a more or less okay way. But nothing is really well done. It’s a Microsoft product. They are famous for business acument, not for user centered design. From a designer’s point of view this is not an unfair or all too biased statement, because a tool (or a person) that does everything… can’t do anything really well. It lacks by definition focus and purpose. So how could it provide it?
I do not only know Word inside-out functionally (as much as this is even possible, because it has so much stuff, versions and variation), I have observed kids and how confused and lost and distracted they get.
The second part of my job was teaching them to write scientific papers with Word. It was so painful to get them away from fumbling with fonts colors and functions that the thought set it: “I wish there was something like a type writer for computers.” Word has no focus structurally and it provides no focus in the act of writing. And don’t tell me again “But I am fine.” This is the recurring topic. There is the individual perspective, and it’s different every time. A lot of people are fine with Word. Some are even excited about it, apparently. Nickelback has fans. But a lot are not. And that it’s a standard now has nothing to do with its excellence but with business strategy and often dirty tactics. And that shows as well if you have the eye for it.
We have an old comparison of Word vs iA Writer. I should update it. But it’s not (just)
about us.
There are plenty of great writing apps that have different purposes: Journaling, note taking, complex structure handling, film scripts, networked thought and collaboration. Some use markdown, some do not. Some are so focused that they have implement polish character name generators! 
We try or best to make the writing process as seamless as possible, so you can focus on what you want to say, rather than dealing with the app itself; we offer very specific tools for professional writers like detecting fillers and syntax highlight. Not everyone needs that and again one or the other has special opinions on the exact color of what, but it’s a very focused app. No Visual Basic Editors.
The strength of Markdown is not writing into a format. The strength of writing into a paper format lays with layout apps. Personal experience matters but different apps have different purposes, and logically nothing can excel at everything.
The strength of markdown lies in the portability of structured digital text. Unlike Word which for decades tried to monopolize writing in its proprietary format (luckily it’s not that obnoxious anymore, thank you EU!), markdown apps allow you to do different things in different apps, different platforms, different channels with the same text without losing anything.
Markdown is also great for focusing on content over form. It would be great for business communication (including paper letters, with MD and tempting they would be fully CI/CD compliant), but the business domain is fully controlled by the Empire. And there is no way in hell that companies embrace a more suitable format, individually. People are so used to MS Word that they perceive it as useable and useful. Which is funny if you take a step back. But that’s how it is.
You may like or hate it, personally. But that doesn’t make Word exceptionally great at anything except that previously mentioned quality: being-sort-of-okay-at-most-things.