Don't install npm packages globally

This article needs significantly more content to be useful to a user genuinely curious about the topic. Answers to the following questions would improve its usefulness:

Why would someone normally install globally? What are the advantages to installing globally? How can these advantages be reproduced, without global installation? Are there disadvantages to using scripts? [... etc ...]

Creating content for the sake of creating content is as useful as saying "don't do it" in regards to global npm installs.