D&D 5th Edition: 8th Revision and Counting

[Kurald Galain]

"Misses doing ½X damage" works out mathematically to the same end result as "50% of attacks hit, doing X damage".

Only if you assume that 50% of attacks hit. That is not at all the case. If a low-level kobold attacks an armored experienced fighter, then a 10% chance to hit is more reasonable.