But for server installations (auto-signing, checking, etc.) you are often directed to GnuPG 1 because "less dependencies". Also "apt install gnupg" / "dnf install gnupg" both give you version 1 on the most recent Ubuntu/Fedora.
For desktop usage many prefer GnuPG 2.0, because they fear compatibility issues that the new 2.1 key storage format could have with 3rd party software, and you can't go back (at least this is the reason why the Homebrew maintainers still default to 2.0, but at least not to version 1 anymore since a few days).
So you have a mess of 3 stable versions, all used by many at the same time.
For desktop usage many prefer GnuPG 2.0, because they fear compatibility issues that the new 2.1 key storage format could have with 3rd party software, and you can't go back (at least this is the reason why the Homebrew maintainers still default to 2.0, but at least not to version 1 anymore since a few days).
So you have a mess of 3 stable versions, all used by many at the same time.