Two other common use cases I have for more advanced software like 7-Zip, beyond compression ratio, are the ability to select AES for encryption (vs the weak old school ZipCrypto) and the ability to tar things.
Sometimes I don't want compression at all, so I'll tar instead, just because it's easier to work with one big file over many small ones. Tar is also convenient for beaming groups of files over netcat.
I love the fact in 7zip you can open disk images and it can read ext4 and other filesystems to extract files out of them and write files back into them
You can create zero compression zips in Windows Explorer. It's probably the most common use-case for their "create" step (people just creating a quick zip to send projects, etc to each other).
But yes, if you specifically want a tarball you'll still need tar.
Don’t forget the need to send “naughty” files through corporate email. If you attach a .py/.bat/must-be-a-virus-extension, the entire message can get silently blocked. Compressing it with a trivial password can be mandatory.
Sometimes I don't want compression at all, so I'll tar instead, just because it's easier to work with one big file over many small ones. Tar is also convenient for beaming groups of files over netcat.