> you don't need to stay on the latest version

Homebrew only provides support for Apple-supported macOS versions though.

I found out the hard way when a brew upgrade on Mojave (the last macOS version to support 32-bit apps) took hours to complete, because it was compiling plenty of stuff from source.

This isn't a complaint. I understand that it doesn't make much sense to provide precompiled binaries for obsolete macOS versions that are likely to have security vulnerabilities.