/bin/bash -c "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/master/install.sh)"

Why does Homebrew
( /bin/bash -c "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/master/install.sh)") install
python on my Mac. macOS already has 2.7 (to go away in the future), and I install python 3.8 from Python.org. As installing text flys up my screen, it looks like python 3.7 gets installed.

Probably because it’s needed for something you’re trying to install. Homebrew can’t reliably know about what you have installed other than what’s part of the OS so if something is needed that isn’t provided by macOS it’ll be installed.

That seems to be a rather huge assumption by the install. Heck Python is now at 3.8.3 and 3.9 is being developed.
It seems to me that Python is one of those things best done by the user and not Homebrew.

It seems to me that Python is one of those things best done by the user and not Homebrew.

We did this for a long time and stopped because it broke a lot of things and maintainers were spending more time figuring out user’s build systems instead of working on Homebrew. Generally speaking, people expect a package manager to install things on their behalf so their software works, without needing to know the details of e.g. the provenance of their Python installation. This remains true even for a non-system package manager like Homebrew.

If you don’t want that, see this page for some historical context and how you can use system or upstream Python builds for your custom formulae. Alternatively, consider using a different package manager that more suits your needs, or language-specific software such as pyenv.

The only reason that I used Homebrew is that is is a requirement for installing Orth4XP.
I also requested that this topic be deleted because I ran the master install again and no additional python was installed. It was in a unix.sh step that was written by the developer which made for a never ending terminal window full of install messages.