Maybe it's a throwback to years gone by when they could splinter horribly. The original Beman carbons were pretty deadly when they splintered. Modern decent carbons are not the same animal ( I put the caveat in to eliminate the cheap pultruded arrows or converted tent poles people really ought to know better than to buy ).A lot of field courses don't like carbons because of the way they can break up.
It's not an issue on NFAS field courses and you tend to only see kids/beginners shooting Allies, there's the odd person who shoots them but I would go with 90+% are either wood or carbon as a rough guess and I've not known a problem with them.
On one shoot hosted by Liberty archers we even shoot at a steel target (Robodeer) where anything except the kill zone will shatter your arrow - you just pick the busted arrow up and stick it in the top of the boss to be collected later, no issues - just great fun, everyone takes a couple of cr*p arrows knowing they're likely to be destroyed.