To be absolutely clear: what Homebrew is doing here is consistent with what
every other system package manager does. If you've ever done `do-release-upgrade` to bump your Ubuntu LTS, you'll have run into the exact same problem.
The only difference is that Homebrew doesn't have a stable system distribution to pin to (we're not Apple, and we have no say over macOS's development), so we make upgrade decisions for packages like Python based on their stability with our packaged ecosystem. It's a poor practice to use your system Python distribution for any sort of virtualized development environment, and Homebrew behaves identically to every other system package manager in that regard.
Please keep in mind that we're a community of volunteers answering to millions of users. Your idea of "user hostile" is our idea of "simple for the sake of preserving our sanity."