You're right, I've conflated MSI with .CAB which was used back in the floppy era.
CAB is a format like ZIP. MSIs are fun because they use CAB files under the hood. But also a database format from the Microsoft JET Engine that was an ancient predecessor to the Windows Registry and contemporary/counterpart of the Office Access format at the time.
It's really interesting to compare MSI to MSIX which is ZIP/XML instead of CAB/weird JET DB file.