InstallShield predates Windows Installer by about a decade.
It’s funny though, because despite MSI coming into existence the problems InstallShield fix didn’t really change much.
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.