Comment by freedomben

Agree with all the reasons, but number 1 is really the most important:

> 1. It makes it easy to learn how to structure a program in a pure way, which is hard to do in languages that offers you a easy way out.

When there's an escape hatch, you will reach for it at some point. It helps with getting things done, but you never end up really confronting the hard things when you have that, and the hard things are an important part of the learning/benefit.