I've been thinking about some cases of fanaticism over a software tool.
One case results from investment (time) in a steep learning curve. Making such a investment leads to a situation where the mere thought of -changing- tools generates a strong unconscious rejection. I believe this is an evolved response. It's understandable. The more you invest, the more you loose by change.
I'm thinking in emacs vs vim, and both of them vs everything else. (Disclaimer, I use none of them)