For Windows I would say it is. Windows doesn't come with vi, nano, or any other terminal text editor, and some kind of text editor is needed for pretty much anything you would do with a computer.
I have never seen non techie users open notepad or edit config files. In fact I've heard people say that Notepad sucks and that MS Word is better, meaning they are so non techie they can't imagine a use case for notepad.
I doubt this is the paradigm that Microsoft would like to promote. Interestingly, my limited interactions will Windows 10 I haven't had the chance or need to use a text editor.
There is also write.exe or, just a suggestion, buy MS Office Word in a package deal for like ninety nine bucks. I can see why notepad might be deemed unimportant by Microsoft with both a commercial alternative to push and a more powerful editor also built in. (Assuming write.exe is still in W11, last I used was 7 I think.)
Those applications are absolutely not suitable for text editing because they have a tendency to mangle the text encoding and other CR/LF characters.
(I generally don't think it's too odd for an OS to ship with a text editor of some kind. I don't use notepad much but there are a few times that it's been a life saver.)
You edit config files in Windows? Registry is all the rage there, unless you use tools made to be cross-platform (which, for devs, is obviously a lot, but I can see an argument that notepad isn't that important to the OS).