It's more about superstition. My laptop works right now ... mostly ... I don't want to poke at it unless I have a very good reason.
Because something always breaks and then you are in a world of pain as in this XKCD about setting up dual-booting with BSD http://xkcd.com/349/
I am actually the opposite. I have had brittle setups in the past and I found myself trying less and less because the past was becoming more precious.
Now I destroy and recreate as often as feasible. Never go more than a 9 months w/o a rebuild.
Something there doesn't sound right (and brings up questions about how do you even manage so many random libraries and whatnot).
Dependency and package management isn't that difficult and when I wipe my hdd/ssd it usually takes me some 30 minutes to get my generic environment bootstrapped and up to date (with a mixture of shell scripts and brew install `my-package-list.txt`). After that, each project takes few minutes to download all deps/libs with some dependency management tool.
Just the same way I would imagine that you've got your oh-my-zsh config version controlled (speaking of oh-my-zsh, I'd like to also mention prezto[0]!)
0: https://github.com/sorin-ionescu/prezto