Even a fairly vanilla ROS installation has a deep dependency tree— there are any of several dozen major packages which can at any moment release a new major version and break us.
If you rely heavily on Homebrew in this way you should instead vendor all the formulae you depend on so that updates do not happen without your manual intervention.
That's basically what is done, on a piecemeal basis as things break, but it would be untenable to do it for the dozens of system dependencies, especially when I don't have the resources to set up a whole parallel bottling infrastructure.
In the end, most ROS Mac users still choose an Ubuntu, Debian, or Fedora VM— having a stable set of underlying packages is worth the tradeoff in convenience and performance.
As I've mentioned before: I'm afraid that's a problem for ROS to solve, not Homebrew. We make these options available to you regardless of whether you choose them. Sorry!
Yup, totally understand. I'm looking into Nix and other solutions to see if there might be something else that's a better fit for this use case than Homebrew.
Exactly. That's how I managed an app (basically a port of lots of stuff from Linux) for macOS years ago. I depended upon MacPorts as my build system, lots of patching to match our in-house build on Linux... but wrapped an entire Python etc universe inside the app.
Even a fairly vanilla ROS installation has a deep dependency tree— there are any of several dozen major packages which can at any moment release a new major version and break us.