Comment by alex1

Mostly because of my (perhaps irrational) OCD in not wanting to touch global system paths or files, even though under FHS /usr/local is where you're supposed to install manually-managed libraries and binaries. I believe Homebrew likes to have its path owned by you instead of root, so I think it makes more sense to have stuff that's going to be owned by me to be in my home folder rather than /usr/local.