I think it makes sense from a programming view. When you have a document, you can add all the media files and pack them together as one archive. Then the program sets the filename to .docx so everyone knows that they need an office program to open that file.
For the users, all you need to know is what program can open which files. If every document would be named .zip, you would have no idea if it was a spreadsheet or slides for your presentation.
I got that from the other answers. I was just very confused why I’d have to rename them to “.zip”.
I still don’t get why it is “most” files.
You don’t have to rename them, doing so would just make windows default to using the builtin zip extractor.
If you have 7-zip you can just right click the file you wan to explore and try to extract it.
