[BlackFingolfin]

That's a really weak justification. For most of those "braindead" packages, it is actually fairly easy to get them to install into arbitrary locations. After all, both Fink and MacPort have been doing that with great success for over a decade.

Sadly, you are correct about "not every single Homebrew formula has actually been tested with a non-/usr/local install path". In fact, while there are many Homebrew formulas of great quality, my impression is that there are also m many of rather poor quality, with other problems in them. E.g. just yesterday, I discovered that the Homebreak lmdb formula does not build properly versioned shared libraries -- because upstream didn't, and the packager either didn't notice or didn't care to fix it

I rarely (if ever) this kind of issue with MacPort and Fink, which try hard to avoid such problems (at the cost of a higher entry barrier for packagers -- for better or worse). Mind you, I am not everything is golden with them, either.

Disclaimer: I've been involved with the Fink project since OS X 10.1 or so.