I think the dynamics in play in a hailstorm and a gable roofing system with 3 tab asphalt shingles is instructive here.
- The hailstorm is the (lacking in uniformity) AoE effect.
- The 3 tab asphalt shingles are the layers of protection and "meat" of the target creature; the armor - layers of asphalt (and possibly mineral fillers) - protects the meat - base matting (of paper or fiberglass + resin).
I'll try to keep this short and accessible without losing too much in the process:
Industry standards (created and continuously verified by field research and testing and considerable publishing in peer-reviewed journals) have defined functional hail damage to asphalt roofs as: "a dimunition of the water shedding ability of the shingle or the reduction in the long-term service life of the shingle."
There are multiple phenomenon in play here that dictate damage to the base matting (the meat) of the shingle which would compromise it:
1 - The mitigatory effects of the top layers of the shingle (the armor class!). As shingles get old, they dry out and become brittle and they suffer natural granule loss due to exposure to various elements of aging. Once the shingle has passed its useful life, it is extremely susceptible to events like thermal shock or hail strikes from smaller than 1.25 " stones.
2 - Industry standards puts 1.25" diameter stones as the minimum threshold for damaging asphalt shingles.
3 - The structural integrity of the hailstone itself. If a hailstone is "soft", it will leave spatter marks (removing oxidation, dirt, algae but causing no functional damage). Hailstones that are "hard" may cause indentation, inducing granule loss and possibly fracturing the base matting. The deeper the updrafts of the storm, the more likely the hail will be of the harder variety (as it will have cycled upward into freezing temperatures more often).
4 - The angle of impact of the hailstone on the roof. The wind has a large role to play here. If the wind forces the hailstones into an oblique angle, the energy transfer of the impact of the stone onto the shingle is mitigated (progressively with the obliqueness of the angle). A strike at a right angle to the roofing system will create maximum energy transfer and increase the possibility of damages to the base matting of the shingle significantly.
5 - Hailstorms are extremely local events. You can have extreme updrafts (causing larger, harder stones) in one place and literally right outside these extreme updrafts, the upward moving wind can be marginal. Further, just as above with updrafts, the horizontal wind field is also local.
This creates a scenario where a neighbor's roofing system can be "missed (utterly undamaged or at least functionally undamaged)" by a hailstorm while right next door the old roof (beyond its useful life), with micro-updrafts and little to no horizontal wind to make the angle of impact oblique, is damaged significantly.
Bottom line, AoE effects and their damage are not remotely uniform and, in the real world, are subjected to a large number of "contests" that trigger classification of "a hit (with damage)".