I owned zip folders for a while during the windows Vista days. I could have sworn the code was originally purchased, not written by someone at Microsoft. Honestly, it looked like it had been run through an obfuscator. I assumed that the original author had done that to ensure it was difficult for Microsoft to make changes/improvements.
I may be misremembering, but Dave has spoken on his Dave's Garage Youtube channel about running a separate software business selling small utilities and later selling some of them to Microsoft. This might have been one of them. A quick search confirms that he also claims that here:
He talks about it in one of his videos. The zip directory was a product of a side hustle of his, which Microsoft then bought out. In the video he comments how much easier it was to integrate when he had access to more internal apis.
I still have nightmares about that code. :)