Cask can be likened to venv or maven for Emacs Lisp development,
although, as with all things emacs, is decidedly less sophisticated
(but no less arcane).

Cask provisions dependencies within a sandbox via a user-defined
"Cask" file analogous to requirements-dev.txt or pom.xml.

Cask does not absolve you of having to learn emacs's command flags.
Cask only constructs the sandbox, one for each version of emacs
you choose to test.