How is it surprising to people that zip and XML are in stdlibs for a programming language?
Btw, you should have looked at dotnet for this as well. There is a very good library ( DocumentFormat.OpenXml) that can handle all docx/xlsx/pptx files. And dotnet can ship standalone binaries (though AOT probably won't work).
Difficult to square the author's surprise with the later comment "I have my fair share of building a Java desktop application and know jpackage and alike very well"
You can't get very far in Java development without working with .jar files (which are zip archives).
https://github.com/dotnet/Open-XML-SDK
First party from Microsoft; feels like it would be the way to go.
Many runtimes/languages rely on third party deps for that. Also plenty of devs think the stdlib should be as lean as possible.
Personally, I think there should be a balance. The direct consequence of a barebones stdlib is NPM and having to download hundreds of dependencies for a hello world.