Why are local modules used in gulp, grunt?

Question

Grunt.js

Actually the question is in the title.
Yes, I understand that there are old projects and old versions are needed for them, but is it possible to check if there is a locally installed module and use it, otherwise global?
What other reasons to use locally installed modules?

Answer 1

You may end up with some packages using different versions of the same package. Moreover, the versions may be incompatible with each other (major versions are different). But what if you updated one package and it dragged along fresh dependencies that turned out to be incompatible with other modules? You will get tired of resolving module versions. It's easier to keep node_modules nearby.