any idea what the heck Microsoft is doing with this brew install? I found this install script for msodbcsql at odbc-driver-13-1-for-macos-released

The relevant contents are:

/usr/bin/ruby -e “$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/master/install)“
brew tap microsoft/msodbcsql https://github.com/Microsoft/homebrew-mssql-release
brew update
brew install msodbcsql
#for silent install ACCEPT_EULA=y brew install msodbcsql


The part I am confused about is the first line.  When I run it gives this output:

$ /usr/bin/ruby -e "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/master/install)"
==&gt; This script will install:
/usr/local/bin/brew
/usr/local/share/doc/homebrew
/usr/local/share/man/man1/brew.1
/usr/local/share/zsh/site-functions/_brew
/usr/local/etc/bash_completion.d/brew
/usr/local/Homebrew
==&gt; The following existing directories will be made group writable:
/usr/local/bin
/usr/local/include


The way I read this is that their install instructions are not just for msodbcsql using homebrew, they are geared towards installing homebrew first, then msodbsql.  

Is this common practice, or just some MS cluelessness?

Note:  I use macports usually, so I took care to install homebrew in my home directory, so perhaps a standard install of homebrew would not have resulted in their script wanting to trample all over my system.
That's the standard way of installing Homebrew. Microsoft seems to have written an installer which relies on Homebrew being installed, so it makes sense to install it first.