The default behavior to update everything when installing anything is bad UX, and the fact it's hidden behind an environment variable is bad design. The argumen

The default behavior to update everything when installing anything is bad UX, and the fact it's hidden behind an environment variable is bad design. The argument behind the behavior is divorced from reality, in my opinion. It was broken on multiuser systems for a long while, I'm not sure if that's still the case. The requirement to write your package as some ruby scripts is also a bit of a pain, compared to other package managers where you just need a small config file (if at all).