Re: [found the culprit]

[Richard Stallman]

[[[ To any NSA and FBI agents reading my email: please consider    ]]]
[[[ whether defending the US Constitution against all enemies,     ]]]
[[[ foreign or domestic, requires you to follow Snowden's example. ]]]

I agree with you about what Z should do, but there is an additional
reason.

The meaning of Z is to compress or uncompress.  Extracting an archive is
a different operation; it is semantically incoherent for Z to extract
an archive.

If we want a Dired command to extract archives, we should add one.
It can handle .tgz files as well as .tar files and other archive types.

-- 
Dr Richard Stallman
President, Free Software Foundation (https://gnu.org, https://fsf.org)
Internet Hall-of-Famer (https://internethalloffame.org)