From the macOS 10.15 beta release notes, under the "Scripting Language Runtimes" section:

Apple has removed the packages that are using GPLv3 as the licensing isn’t compatible with the rights that Apple is willing to give out. It’s the same reason why the PS4 is based on BSD. The license allows a lot of freedoms to commercial users who don’t want to give out source code.

Python, bash, ruby, etc, these have been out of date on macOS for years because Apple will not use newer versions that are licensed under v3 of the GPL.

Their removal was inevitable. The one thing that has me a little worried is homebrew as we’ll need to install ruby first, Apple should make their own package manager for the mac, but we been asking for years and years and just won’t happen, so 2 step homebrew installation it is (maybe a new installation script for homebrew will solve this?)