I would add two additional reasons to crimp rifle ammo:
1. For lever action rifles.
2. Big game rifles 458 ect or rifles chambered in other straight walled cases such as 45-70, 44mag, 444 marlin, 45 colt, 357 mag ect.

Normally in a bolt action rifle bottle necked cartriges do not require a crimp. Crimping could cause pressures to increase. Also Ive read its not safe to crimp bullets which do not have a crimping grove.

I hope this helps.