Why does brew has to compile files instead of simply installing binaries

Question

I simply did a brew upgrade and ended up with the following:

==> Reinstalling pyside
Warning: Your Xcode (12.3) is outdated.
Please update to Xcode 13.2.1 (or delete it).
Xcode can be updated from the App Store.

==> Installing dependencies for pyside: ninja and llvm
==> Installing pyside dependency: ninja
==> Pouring ninja--1.11.1.big_sur.bottle.tar.gz
🍺  /usr/local/Cellar/ninja/1.11.1: 10 files, 453.2KB
==> Installing pyside dependency: llvm
==> Pouring llvm--15.0.6.big_sur.bottle.tar.gz
🍺  /usr/local/Cellar/llvm/15.0.6: 6,411 files, 1.3GB
==> Installing pyside
==> cmake -S . -B build -DCMAKE_CXX_COMPILER=clang++ -DCMAKE_PREFIX_PATH=/usr/local/opt/qt/lib -DPYTHON_EXECUTABLE=/usr/local/opt/[email protected]/bin/python3.10 -DBUILD_TESTS=OFF -DNO_QT_TOOLS=yes
==> cmake --build build
==> Fetching pyside
==> Downloading https://download.qt.io/official_releases/QtForPython/pyside6/PySide6-6.4.0.1-src/pyside-setup-opensource-src-6.4.0.tar.xz
==> Downloading from https://ftp.fau.de/qtproject/official_releases/QtForPython/pyside6/PySide6-6.4.0.1-src/pyside-setup-opensource-src-6.4.0.tar.xz
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Couldn't brew fetch and install pyside binaries instead of having to wait hours till the compilation finishes?

Answer 1

Posting this as an answer for future reference. From the Homebrew Documentation: FAQ (Frequently Asked Questions provided by @Martin R in a comment.

Why do you compile everything?

Homebrew provides pre-built binary packages for many formulae. These are referred to as bottles and are available at https://github.com/Homebrew/homebrew-core/packages.

If available, bottled binaries will be used by default except under the following conditions:

• The --build-from-source option is invoked.
• No bottle is available for the machine’s currently running OS version. (Bottles for macOS are generated only for supported macOS versions.)
• Homebrew is installed to a prefix other than the default (although some bottles support this).
• Formula options were passed to the install command. For example, brew install will try to find a bottled binary, but brew install --with-foo will trigger a source build.

We aim to bottle everything.