I do it because I spend a lot of money and time getting a rifle set up like I like with a new barrel and it's a small investment to ensure it's taken care of. Maybe it helps, maybe it doesn't, but it sure doesn't hurt. The barrel makers mostly say do it, pretty much all the better gunsmiths say do it, and most of the best benchrest shooters say they do it, so I do it. It doesn't take much time and gives me a chance to chronograph some loads and get my scope zeroed. Unless someone can give me a reason why it's bad to break in a barrel I'll continue to do it. Saying "it's not needed" isn't good enough, give me a reason why it's not good for my barrel.

Barrel makers say it's good.
Top gunsmiths say it's good.
Top benchrest shooters say it's good.

Drunk guys making youtube videos throwing rifles against rocks say it's bad.

Which one do I trust?