Kyle Defoor posted a little article on over magnification of rifle scopes.
Shawn and I often talk about this. It is amazing the silly combination that are made by people who choose way too much magnification for their firearms intended role.
Too much magnification on the combat rifle slows down target acquisition, follow up shots, moving from target to target, etc. It is not uncommon to see someone slap a 20x scope on their AK just to find that it makes for a poor precision rifle, and is no longer fast or handy up close.
On the competition or precision rifle too much magnification can cause issues when there is mirage. Sure that March 80 power scope can read the numbers on a IBS 1000 yard target on a perfect morning, most of the time our 1000 yard competition shooters are using less then 20x due to normal conditions here in Florida.
Excessive magnification hurts, not helps the shooter.