There is a valid viewpoint that suggests that in larger sizes, barbless hooks do more damage than barbed by virtue of the fact that they can cut/tear the mouth more easily.
I think there are reasonable arguements both ways.
Poor angling damages fish, not hooks !
As an argument hasn't been put forward by me Sam, not certain how my comment could convince or not!
Theres been other threads on here discussing this and the consensus seems to be that powerful rods in inexperienced hands, bolt rigging with heavy weights, not playing fish properly, braid etc are also factors.
I've seen the threads and don't draw the same conclusions. There are more than the odd one or two, that are extremely anti-carping/carpers, that shout very loudly about powerful rods, bolt rigs, heavy weights etc. However, to suggest that there is a consensus is wide of the mark. If we come closer to that consensus than I believe we do, it's primarily because there aren't that many out and out carpers on here.
No one has managed to explain to me why the worst venues for seeing mouth damage are commercials where barbed hooks are banned, no one uses "proper" carp tactics and often there's no matches to speak of.
Fair enough Sam, thats why i said "factors" rather than "causes".
I think stronger lines and powerful rods are a key difference between now and say 30 years ago when mouth damage was rarer - but also frequency of capture is a lot greater nowadays on pressured waters. That would be my hypothesis as to why fish on pressured commercials with barbless hooks rules show mouth damage. 30 years back it was common for anglers to hook a carp but get snapped off due to using lighter lines and inadequate tackle as they were targeting tench or bream etc.