Well, it doesn't need it, however with long range rifles the projectile will act differently with a cold bore (barrel) and if the shooter doesn't know that the shot could miss its intended point of impact (resulting in a messy or inhuman kill) which is why I do the pre-work as per this post to know how the projectile will behave and account for it when required.

I'm glad you find it interesting enough to take a read and that you manage to find something to learn. Most people get their opinions on firearms from the movies or video games both of which do not represent correctly.